diff --git a/api/handler/book.go b/api/handler/book.go
index 2266243..a585c58 100644
--- a/api/handler/book.go
+++ b/api/handler/book.go
@@ -17,7 +17,7 @@ import (
 	"github.com/gorilla/mux"
 )
 
-func listBooks(service book.UseCase) http.Handler {
+func listBooks(service book.Repository) http.Handler {
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		errorMessage := "Error reading books"
 		var data []*book.Book
@@ -58,7 +58,7 @@ func listBooks(service book.UseCase) http.Handler {
 	})
 }
 
-func createBook(service book.UseCase) http.Handler {
+func createBook(service book.Repository) http.Handler {
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		errorMessage := "Error adding book"
 		var input struct {
@@ -107,7 +107,7 @@ func createBook(service book.UseCase) http.Handler {
 	})
 }
 
-func getBook(service book.UseCase) http.Handler {
+func getBook(service book.Repository) http.Handler {
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		errorMessage := "Error reading book"
 		vars := mux.Vars(r)
@@ -143,7 +143,7 @@ func getBook(service book.UseCase) http.Handler {
 	})
 }
 
-func deleteBook(service book.UseCase) http.Handler {
+func deleteBook(service book.Repository) http.Handler {
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		errorMessage := "Error removing bookmark"
 		vars := mux.Vars(r)
@@ -163,7 +163,7 @@ func deleteBook(service book.UseCase) http.Handler {
 }
 
 //MakeBookHandlers make url handlers
-func MakeBookHandlers(r *mux.Router, n negroni.Negroni, service book.UseCase) {
+func MakeBookHandlers(r *mux.Router, n negroni.Negroni, service book.Repository) {
 	r.Handle("/v1/book", n.With(
 		negroni.Wrap(listBooks(service)),
 	)).Methods("GET", "OPTIONS").Name("listBooks")
diff --git a/api/handler/loan.go b/api/handler/loan.go
index d1f1b82..ae3c3ba 100644
--- a/api/handler/loan.go
+++ b/api/handler/loan.go
@@ -6,7 +6,7 @@ import (
 
 	"github.com/eminetto/clean-architecture-go-v2/domain/entity/user"
 
-	"github.com/eminetto/clean-architecture-go-v2/domain/loan"
+	"github.com/eminetto/clean-architecture-go-v2/domain/usecase/loan"
 
 	"github.com/eminetto/clean-architecture-go-v2/domain"
 
@@ -17,7 +17,7 @@ import (
 	"github.com/gorilla/mux"
 )
 
-func borrowBook(bService book.UseCase, uService user.UseCase, loanService loan.UseCase) http.Handler {
+func borrowBook(bService book.Repository, uService user.Repository, loanService loan.UseCase) http.Handler {
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		errorMessage := "Error borrowing book"
 		vars := mux.Vars(r)
@@ -66,7 +66,7 @@ func borrowBook(bService book.UseCase, uService user.UseCase, loanService loan.U
 	})
 }
 
-func returnBook(bService book.UseCase, loanService loan.UseCase) http.Handler {
+func returnBook(bService book.Repository, loanService loan.UseCase) http.Handler {
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		errorMessage := "Error returning book"
 		vars := mux.Vars(r)
@@ -98,7 +98,7 @@ func returnBook(bService book.UseCase, loanService loan.UseCase) http.Handler {
 }
 
 //MakeLoanHandlers make url handlers
-func MakeLoanHandlers(r *mux.Router, n negroni.Negroni, bService book.UseCase, uService user.UseCase, loanService loan.UseCase) {
+func MakeLoanHandlers(r *mux.Router, n negroni.Negroni, bService book.Repository, uService user.Repository, loanService loan.UseCase) {
 	r.Handle("/v1/loan/borrow/{book_id}/{user_id}", n.With(
 		negroni.Wrap(borrowBook(bService, uService, loanService)),
 	)).Methods("GET", "OPTIONS").Name("borrowBook")
diff --git a/api/handler/loan_test.go b/api/handler/loan_test.go
index 6c0ef80..7075dce 100644
--- a/api/handler/loan_test.go
+++ b/api/handler/loan_test.go
@@ -16,7 +16,7 @@ import (
 	"github.com/codegangsta/negroni"
 	bmock "github.com/eminetto/clean-architecture-go-v2/domain/entity/book/mock"
 	umock "github.com/eminetto/clean-architecture-go-v2/domain/entity/user/mock"
-	lmock "github.com/eminetto/clean-architecture-go-v2/domain/loan/mock"
+	lmock "github.com/eminetto/clean-architecture-go-v2/domain/usecase/loan/mock"
 	"github.com/golang/mock/gomock"
 	"github.com/gorilla/mux"
 	"github.com/stretchr/testify/assert"
diff --git a/api/handler/user.go b/api/handler/user.go
index 6043c36..784ed97 100644
--- a/api/handler/user.go
+++ b/api/handler/user.go
@@ -18,7 +18,7 @@ import (
 	"github.com/gorilla/mux"
 )
 
-func listUsers(service user.UseCase) http.Handler {
+func listUsers(service user.Repository) http.Handler {
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		errorMessage := "Error reading users"
 		var data []*user.User
@@ -58,7 +58,7 @@ func listUsers(service user.UseCase) http.Handler {
 	})
 }
 
-func createUser(service user.UseCase) http.Handler {
+func createUser(service user.Repository) http.Handler {
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		errorMessage := "Error adding user"
 		var input struct {
@@ -107,7 +107,7 @@ func createUser(service user.UseCase) http.Handler {
 	})
 }
 
-func getUser(service user.UseCase) http.Handler {
+func getUser(service user.Repository) http.Handler {
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		errorMessage := "Error reading user"
 		vars := mux.Vars(r)
@@ -143,7 +143,7 @@ func getUser(service user.UseCase) http.Handler {
 	})
 }
 
-func deleteUser(service user.UseCase) http.Handler {
+func deleteUser(service user.Repository) http.Handler {
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		errorMessage := "Error removing user"
 		vars := mux.Vars(r)
@@ -163,7 +163,7 @@ func deleteUser(service user.UseCase) http.Handler {
 }
 
 //MakeUserHandlers make url handlers
-func MakeUserHandlers(r *mux.Router, n negroni.Negroni, service user.UseCase) {
+func MakeUserHandlers(r *mux.Router, n negroni.Negroni, service user.Repository) {
 	r.Handle("/v1/user", n.With(
 		negroni.Wrap(listUsers(service)),
 	)).Methods("GET", "OPTIONS").Name("listUsers")
diff --git a/api/main.go b/api/main.go
index 6aa4be4..acc03c0 100644
--- a/api/main.go
+++ b/api/main.go
@@ -11,7 +11,7 @@ import (
 
 	"github.com/eminetto/clean-architecture-go-v2/pkg/password"
 
-	"github.com/eminetto/clean-architecture-go-v2/domain/loan"
+	"github.com/eminetto/clean-architecture-go-v2/domain/usecase/loan"
 
 	"github.com/eminetto/clean-architecture-go-v2/domain/entity/user"
 
@@ -38,12 +38,12 @@ func main() {
 	defer db.Close()
 
 	bookRepo := book.NewMySQLRepoRepository(db)
-	bookService := book.NewService(bookRepo)
+	bookService := book.NewRepository(bookRepo)
 
 	userRepo := user.NewMySQLRepoRepository(db)
-	userService := user.NewService(userRepo, password.NewService())
+	userService := user.NewRepository(userRepo, password.NewService())
 
-	loanService := loan.NewService(userService, bookService)
+	loanService := loan.NewUseCase(userService, bookService)
 
 	metricService, err := metric.NewPrometheusService()
 	if err != nil {
diff --git a/cmd/main.go b/cmd/main.go
index d4ab153..00ddbea 100644
--- a/cmd/main.go
+++ b/cmd/main.go
@@ -41,7 +41,7 @@ func main() {
 	}
 	defer db.Close()
 	repo := book.NewMySQLRepoRepository(db)
-	service := book.NewService(repo)
+	service := book.NewRepository(repo)
 	all, err := service.Search(query)
 	if err != nil {
 		log.Fatal(err)
diff --git a/domain/entity/book/book.go b/domain/entity/book/entity.go
similarity index 100%
rename from domain/entity/book/book.go
rename to domain/entity/book/entity.go
diff --git a/domain/entity/book/interface.go b/domain/entity/book/interface.go
index 2496a28..cfbe549 100644
--- a/domain/entity/book/interface.go
+++ b/domain/entity/book/interface.go
@@ -21,9 +21,3 @@ type Repository interface {
 	Reader
 	Writer
 }
-
-//UseCase use case interface
-type UseCase interface {
-	Reader
-	Writer
-}
\ No newline at end of file
diff --git a/domain/entity/book/service.go b/domain/entity/book/repository.go
similarity index 53%
rename from domain/entity/book/service.go
rename to domain/entity/book/repository.go
index 682c105..6eecc32 100644
--- a/domain/entity/book/service.go
+++ b/domain/entity/book/repository.go
@@ -7,42 +7,41 @@ import (
 	"github.com/eminetto/clean-architecture-go-v2/domain/entity"
 )
 
-//Service service interface
-type Service struct {
+type repository struct {
 	repo Repository
 }
 
-//NewService create new use case
-func NewService(r Repository) *Service {
-	return &Service{
+//NewRepository create new repository
+func NewRepository(r Repository) *repository {
+	return &repository{
 		repo: r,
 	}
 }
 
 //Create a book
-func (s *Service) Create(e *Book) (entity.ID, error) {
+func (s *repository) Create(e *Book) (entity.ID, error) {
 	e.ID = entity.NewID()
 	e.CreatedAt = time.Now()
 	return s.repo.Create(e)
 }
 
 //Get a book
-func (s *Service) Get(id entity.ID) (*Book, error) {
+func (s *repository) Get(id entity.ID) (*Book, error) {
 	return s.repo.Get(id)
 }
 
 //Search books
-func (s *Service) Search(query string) ([]*Book, error) {
+func (s *repository) Search(query string) ([]*Book, error) {
 	return s.repo.Search(strings.ToLower(query))
 }
 
 //List books
-func (s *Service) List() ([]*Book, error) {
+func (s *repository) List() ([]*Book, error) {
 	return s.repo.List()
 }
 
 //Delete a book
-func (s *Service) Delete(id entity.ID) error {
+func (s *repository) Delete(id entity.ID) error {
 	_, err := s.Get(id)
 	if err != nil {
 		return err
@@ -51,6 +50,6 @@ func (s *Service) Delete(id entity.ID) error {
 }
 
 //Update a book
-func (s *Service) Update(e *Book) error {
+func (s *repository) Update(e *Book) error {
 	return s.repo.Update(e)
 }
diff --git a/domain/entity/book/repository_inmem.go b/domain/entity/book/repository_inmem.go
index 8e5a788..1410bea 100644
--- a/domain/entity/book/repository_inmem.go
+++ b/domain/entity/book/repository_inmem.go
@@ -7,27 +7,27 @@ import (
 	"github.com/eminetto/clean-architecture-go-v2/domain/entity"
 )
 
-//IRepo in memory repo
-type IRepo struct {
+//iRepo in memory repo
+type iRepo struct {
 	m map[entity.ID]*Book
 }
 
 //NewInmemRepository create new repository
-func NewInmemRepository() *IRepo {
+func NewInmemRepository() *iRepo {
 	var m = map[entity.ID]*Book{}
-	return &IRepo{
+	return &iRepo{
 		m: m,
 	}
 }
 
 //Create a book
-func (r *IRepo) Create(e *Book) (entity.ID, error) {
+func (r *iRepo) Create(e *Book) (entity.ID, error) {
 	r.m[e.ID] = e
 	return e.ID, nil
 }
 
 //Get a book
-func (r *IRepo) Get(id entity.ID) (*Book, error) {
+func (r *iRepo) Get(id entity.ID) (*Book, error) {
 	if r.m[id] == nil {
 		return nil, domain.ErrNotFound
 	}
@@ -35,7 +35,7 @@ func (r *IRepo) Get(id entity.ID) (*Book, error) {
 }
 
 //Update a book
-func (r *IRepo) Update(e *Book) error {
+func (r *iRepo) Update(e *Book) error {
 	_, err := r.Get(e.ID)
 	if err != nil {
 		return err
@@ -45,7 +45,7 @@ func (r *IRepo) Update(e *Book) error {
 }
 
 //Search books
-func (r *IRepo) Search(query string) ([]*Book, error) {
+func (r *iRepo) Search(query string) ([]*Book, error) {
 	var d []*Book
 	for _, j := range r.m {
 		if strings.Contains(strings.ToLower(j.Title), query) {
@@ -60,7 +60,7 @@ func (r *IRepo) Search(query string) ([]*Book, error) {
 }
 
 //List books
-func (r *IRepo) List() ([]*Book, error) {
+func (r *iRepo) List() ([]*Book, error) {
 	var d []*Book
 	for _, j := range r.m {
 		d = append(d, j)
@@ -69,7 +69,7 @@ func (r *IRepo) List() ([]*Book, error) {
 }
 
 //Delete a book
-func (r *IRepo) Delete(id entity.ID) error {
+func (r *iRepo) Delete(id entity.ID) error {
 	if r.m[id] == nil {
 		return domain.ErrNotFound
 	}
diff --git a/domain/entity/book/repository_mysql.go b/domain/entity/book/repository_mysql.go
index ff345f6..4ab968d 100644
--- a/domain/entity/book/repository_mysql.go
+++ b/domain/entity/book/repository_mysql.go
@@ -9,20 +9,20 @@ import (
 	"github.com/eminetto/clean-architecture-go-v2/domain/entity"
 )
 
-//MySQLRepo mysql repo
-type MySQLRepo struct {
+//mySQLRepo mysql repo
+type mySQLRepo struct {
 	db *sql.DB
 }
 
 //NewMySQLRepoRepository create new repository
-func NewMySQLRepoRepository(db *sql.DB) *MySQLRepo {
-	return &MySQLRepo{
+func NewMySQLRepoRepository(db *sql.DB) *mySQLRepo {
+	return &mySQLRepo{
 		db: db,
 	}
 }
 
 //Create a book
-func (r *MySQLRepo) Create(e *Book) (entity.ID, error) {
+func (r *mySQLRepo) Create(e *Book) (entity.ID, error) {
 	stmt, err := r.db.Prepare(`
 		insert into book (id, title, author, pages, quantity, created_at) 
 		values(?,?,?,?,?,?)`)
@@ -48,7 +48,7 @@ func (r *MySQLRepo) Create(e *Book) (entity.ID, error) {
 }
 
 //Get a book
-func (r *MySQLRepo) Get(id entity.ID) (*Book, error) {
+func (r *mySQLRepo) Get(id entity.ID) (*Book, error) {
 	stmt, err := r.db.Prepare(`select id, title, author, pages, quantity, created_at from book where id = ?`)
 	if err != nil {
 		return nil, err
@@ -65,7 +65,7 @@ func (r *MySQLRepo) Get(id entity.ID) (*Book, error) {
 }
 
 //Update a book
-func (r *MySQLRepo) Update(e *Book) error {
+func (r *mySQLRepo) Update(e *Book) error {
 	e.UpdatedAt = time.Now()
 	_, err := r.db.Exec("update book set title = ?, author = ?, pages = ?, quantity = ?, updated_at = ? where id = ?", e.Title, e.Author, e.Pages, e.Quantity, e.UpdatedAt.Format("2006-01-02"), e.ID)
 	if err != nil {
@@ -75,7 +75,7 @@ func (r *MySQLRepo) Update(e *Book) error {
 }
 
 //Search books
-func (r *MySQLRepo) Search(query string) ([]*Book, error) {
+func (r *mySQLRepo) Search(query string) ([]*Book, error) {
 	stmt, err := r.db.Prepare(`select id, title, author, pages, quantity, created_at from book where title like ?`)
 	if err != nil {
 		return nil, err
@@ -100,7 +100,7 @@ func (r *MySQLRepo) Search(query string) ([]*Book, error) {
 }
 
 //List books
-func (r *MySQLRepo) List() ([]*Book, error) {
+func (r *mySQLRepo) List() ([]*Book, error) {
 	stmt, err := r.db.Prepare(`select id, title, author, pages, quantity, created_at from book`)
 	if err != nil {
 		return nil, err
@@ -125,7 +125,7 @@ func (r *MySQLRepo) List() ([]*Book, error) {
 }
 
 //Delete a book
-func (r *MySQLRepo) Delete(id entity.ID) error {
+func (r *mySQLRepo) Delete(id entity.ID) error {
 	_, err := r.db.Exec("delete from book where id = ?", id)
 	if err != nil {
 		return err
diff --git a/domain/entity/book/service_test.go b/domain/entity/book/repository_test.go
similarity index 93%
rename from domain/entity/book/service_test.go
rename to domain/entity/book/repository_test.go
index 10afb9e..85e91f3 100644
--- a/domain/entity/book/service_test.go
+++ b/domain/entity/book/repository_test.go
@@ -10,7 +10,7 @@ import (
 
 func Test_Create(t *testing.T) {
 	repo := NewInmemRepository()
-	service := NewService(repo)
+	service := NewRepository(repo)
 	u := NewFixtureBook()
 	id, err := service.Create(u)
 	assert.Nil(t, err)
@@ -20,7 +20,7 @@ func Test_Create(t *testing.T) {
 
 func Test_SearchAndFind(t *testing.T) {
 	repo := NewInmemRepository()
-	service := NewService(repo)
+	service := NewRepository(repo)
 	u1 := NewFixtureBook()
 	u2 := NewFixtureBook()
 	u2.Title = "Lemmy: Biography"
@@ -53,7 +53,7 @@ func Test_SearchAndFind(t *testing.T) {
 
 func Test_Update(t *testing.T) {
 	repo := NewInmemRepository()
-	service := NewService(repo)
+	service := NewRepository(repo)
 	u := NewFixtureBook()
 	id, err := service.Create(u)
 	assert.Nil(t, err)
@@ -67,7 +67,7 @@ func Test_Update(t *testing.T) {
 
 func TestDelete(t *testing.T) {
 	repo := NewInmemRepository()
-	service := NewService(repo)
+	service := NewRepository(repo)
 	u1 := NewFixtureBook()
 	u2 := NewFixtureBook()
 	u2ID, _ := service.Create(u2)
diff --git a/domain/entity/user/user.go b/domain/entity/user/entity.go
similarity index 100%
rename from domain/entity/user/user.go
rename to domain/entity/user/entity.go
diff --git a/domain/entity/user/interface.go b/domain/entity/user/interface.go
index eb5f309..b76c6ea 100644
--- a/domain/entity/user/interface.go
+++ b/domain/entity/user/interface.go
@@ -21,9 +21,3 @@ type Repository interface {
 	Reader
 	Writer
 }
-
-//UseCase use case interface
-type UseCase interface {
-	Reader
-	Writer
-}
\ No newline at end of file
diff --git a/domain/entity/user/service.go b/domain/entity/user/repository.go
similarity index 53%
rename from domain/entity/user/service.go
rename to domain/entity/user/repository.go
index a476849..47d5196 100644
--- a/domain/entity/user/service.go
+++ b/domain/entity/user/repository.go
@@ -4,27 +4,29 @@ import (
 	"strings"
 	"time"
 
+	"github.com/eminetto/clean-architecture-go-v2/domain"
+
 	"github.com/eminetto/clean-architecture-go-v2/pkg/password"
 
 	"github.com/eminetto/clean-architecture-go-v2/domain/entity"
 )
 
-//Service service interface
-type Service struct {
+//repository service interface
+type repository struct {
 	repo Repository
 	pwd  password.UseCase
 }
 
-//NewService create new use case
-func NewService(r Repository, pwd password.UseCase) *Service {
-	return &Service{
+//NewRepository create new repository
+func NewRepository(r Repository, pwd password.UseCase) *repository {
+	return &repository{
 		repo: r,
 		pwd:  pwd,
 	}
 }
 
 //Create an user
-func (s *Service) Create(e *User) (entity.ID, error) {
+func (s *repository) Create(e *User) (entity.ID, error) {
 	e.ID = entity.NewID()
 	e.CreatedAt = time.Now()
 	pwd, err := s.pwd.Generate(e.Password)
@@ -36,31 +38,34 @@ func (s *Service) Create(e *User) (entity.ID, error) {
 }
 
 //Get an user
-func (s *Service) Get(id entity.ID) (*User, error) {
+func (s *repository) Get(id entity.ID) (*User, error) {
 	return s.repo.Get(id)
 }
 
 //Search users
-func (s *Service) Search(query string) ([]*User, error) {
+func (s *repository) Search(query string) ([]*User, error) {
 	return s.repo.Search(strings.ToLower(query))
 }
 
 //List users
-func (s *Service) List() ([]*User, error) {
+func (s *repository) List() ([]*User, error) {
 	return s.repo.List()
 }
 
 //Delete an user
-func (s *Service) Delete(id entity.ID) error {
-	_, err := s.Get(id)
+func (s *repository) Delete(id entity.ID) error {
+	u, err := s.Get(id)
 	if err != nil {
 		return err
 	}
+	if len(u.Books) > 0 {
+		return domain.ErrCannotBeDeleted
+	}
 	return s.repo.Delete(id)
 }
 
 //Update an user
-func (s *Service) Update(e *User) error {
+func (s *repository) Update(e *User) error {
 	e.UpdatedAt = time.Now()
 	return s.repo.Update(e)
 }
diff --git a/domain/entity/user/service_test.go b/domain/entity/user/repository_test.go
similarity index 89%
rename from domain/entity/user/service_test.go
rename to domain/entity/user/repository_test.go
index 4c6f004..8f7a1c4 100644
--- a/domain/entity/user/service_test.go
+++ b/domain/entity/user/repository_test.go
@@ -13,7 +13,7 @@ import (
 
 func Test_Create(t *testing.T) {
 	repo := NewInmemRepository()
-	service := NewService(repo, password.NewFakeService())
+	service := NewRepository(repo, password.NewFakeService())
 	u := NewFixtureUser()
 	id, err := service.Create(u)
 	assert.Nil(t, err)
@@ -24,7 +24,7 @@ func Test_Create(t *testing.T) {
 
 func Test_SearchAndFind(t *testing.T) {
 	repo := NewInmemRepository()
-	service := NewService(repo, password.NewFakeService())
+	service := NewRepository(repo, password.NewFakeService())
 	u1 := NewFixtureUser()
 	u2 := NewFixtureUser()
 	u2.FirstName = "Lemmy"
@@ -57,7 +57,7 @@ func Test_SearchAndFind(t *testing.T) {
 
 func Test_Update(t *testing.T) {
 	repo := NewInmemRepository()
-	service := NewService(repo, password.NewFakeService())
+	service := NewRepository(repo, password.NewFakeService())
 	u := NewFixtureUser()
 	id, err := service.Create(u)
 	assert.Nil(t, err)
@@ -74,7 +74,7 @@ func Test_Update(t *testing.T) {
 
 func TestDelete(t *testing.T) {
 	repo := NewInmemRepository()
-	service := NewService(repo, password.NewFakeService())
+	service := NewRepository(repo, password.NewFakeService())
 	u1 := NewFixtureUser()
 	u2 := NewFixtureUser()
 	u2ID, _ := service.Create(u2)
diff --git a/domain/loan/interface.go b/domain/usecase/loan/interface.go
similarity index 100%
rename from domain/loan/interface.go
rename to domain/usecase/loan/interface.go
diff --git a/domain/loan/mock/loan.go b/domain/usecase/loan/mock/loan.go
similarity index 100%
rename from domain/loan/mock/loan.go
rename to domain/usecase/loan/mock/loan.go
diff --git a/domain/loan/service.go b/domain/usecase/loan/usecase.go
similarity index 83%
rename from domain/loan/service.go
rename to domain/usecase/loan/usecase.go
index 6c15d26..3c2acdb 100644
--- a/domain/loan/service.go
+++ b/domain/usecase/loan/usecase.go
@@ -7,22 +7,21 @@ import (
 	"github.com/eminetto/clean-architecture-go-v2/domain/entity/user"
 )
 
-//Service service interface
-type Service struct {
-	uService user.UseCase
-	bService book.UseCase
+type usecase struct {
+	uService user.Repository
+	bService book.Repository
 }
 
-//NewService create new use case
-func NewService(u user.UseCase, b book.UseCase) *Service {
-	return &Service{
+//NewUseCase create new use case
+func NewUseCase(u user.Repository, b book.Repository) *usecase {
+	return &usecase{
 		uService: u,
 		bService: b,
 	}
 }
 
 //Borrow borrow a book to an user
-func (s *Service) Borrow(u *user.User, b *book.Book) error {
+func (s *usecase) Borrow(u *user.User, b *book.Book) error {
 	u, err := s.uService.Get(u.ID)
 	if err != nil {
 		return err
@@ -53,7 +52,7 @@ func (s *Service) Borrow(u *user.User, b *book.Book) error {
 }
 
 //Return return a book
-func (s *Service) Return(b *book.Book) error {
+func (s *usecase) Return(b *book.Book) error {
 	b, err := s.bService.Get(b.ID)
 	if err != nil {
 		return err
diff --git a/domain/loan/service_test.go b/domain/usecase/loan/usecase_test.go
similarity index 97%
rename from domain/loan/service_test.go
rename to domain/usecase/loan/usecase_test.go
index 020c545..1a33620 100644
--- a/domain/loan/service_test.go
+++ b/domain/usecase/loan/usecase_test.go
@@ -19,7 +19,7 @@ func Test_Borrow(t *testing.T) {
 	defer controller.Finish()
 	uMock := umock.NewMockUseCase(controller)
 	bMock := bmock.NewMockUseCase(controller)
-	service := NewService(uMock, bMock)
+	service := NewUseCase(uMock, bMock)
 	t.Run("user not found", func(t *testing.T) {
 		u := user.NewFixtureUser()
 		b := book.NewFixtureBook()
@@ -71,7 +71,7 @@ func Test_Return(t *testing.T) {
 	defer controller.Finish()
 	uMock := umock.NewMockUseCase(controller)
 	bMock := bmock.NewMockUseCase(controller)
-	service := NewService(uMock, bMock)
+	service := NewUseCase(uMock, bMock)
 	t.Run("book not found", func(t *testing.T) {
 		b := book.NewFixtureBook()
 		bMock.EXPECT().Get(b.ID).Return(nil, domain.ErrNotFound)