diff --git a/backend/app/services/auth_service.py b/backend/app/services/auth_service.py
index 4941671..7609358 100644
--- a/backend/app/services/auth_service.py
+++ b/backend/app/services/auth_service.py
@@ -15,13 +15,18 @@ from app.core.auth import (
 )
 from app.models.user import User
 from app.schemas.users import Token, UserCreate
+from app.crud.user import user as crud_user
+from app.core.auth import decode_token, get_token_data
 
 logger = logging.getLogger(__name__)
 
 
 class AuthenticationError(Exception):
-    """Exception raised for authentication errors"""
-    pass
+    """Raised when authentication fails"""
+
+    def __init__(self, message: str = "Authentication failed"):
+        self.message = message
+        super().__init__(self.message)
 
 
 class AuthService:
@@ -40,19 +45,22 @@ class AuthService:
         Returns:
             User if authenticated, None otherwise
         """
-        user = db.query(User).filter(User.email == email).first()
-
+        user = crud_user.get_by_email(db, email=email)
         if not user:
-            return None
+            logger.warning(f"Login attempt failed: user not found for email {email}")
+            raise AuthenticationError("Invalid email or password")
 
         if not verify_password(password, user.password_hash):
-            return None
+            logger.warning(f"Login attempt failed: invalid password for user {email}")
+            raise AuthenticationError("Invalid email or password")
 
-        if not user.is_active:
-            raise AuthenticationError("User account is inactive")
+        if not crud_user.is_active(user):
+            logger.warning(f"Login attempt failed: inactive user {email}")
+            raise AuthenticationError("Inactive user")
 
         return user
 
+
     @staticmethod
     def create_user(db: Session, user_data: UserCreate) -> User:
         """
@@ -66,29 +74,20 @@ class AuthService:
             Created user
         """
         # Check if user already exists
-        existing_user = db.query(User).filter(User.email == user_data.email).first()
+        existing_user = crud_user.get_by_email(db, email=user_data.email)
         if existing_user:
-            raise AuthenticationError("User with this email already exists")
+            logger.warning(f"Registration failed: email already registered {user_data.email}")
+            raise AuthenticationError("Email already registered")
 
-        # Create new user
-        hashed_password = get_password_hash(user_data.password)
+        try:
+            # Create new user using CRUD user
+            user = crud_user.create(db, obj_in=user_data)
+            logger.info(f"New user created: {user.email}")
+            return user
+        except Exception as e:
+            logger.error(f"User creation failed: {str(e)}")
+            raise AuthenticationError("Could not create user")
 
-        # Create user object from model
-        user = User(
-            email=user_data.email,
-            password_hash=hashed_password,
-            first_name=user_data.first_name,
-            last_name=user_data.last_name,
-            phone_number=user_data.phone_number,
-            is_active=True,
-            is_superuser=False
-        )
-
-        db.add(user)
-        db.commit()
-        db.refresh(user)
-
-        return user
 
     @staticmethod
     def create_tokens(user: User) -> Token:
@@ -139,7 +138,6 @@ class AuthService:
             TokenExpiredError: If refresh token has expired
             TokenInvalidError: If refresh token is invalid
         """
-        from app.core.auth import decode_token, get_token_data
 
         try:
             # Verify token is a refresh token
@@ -148,12 +146,17 @@ class AuthService:
             # Get user ID from token
             token_data = get_token_data(refresh_token)
             user_id = token_data.user_id
+            if not user_id:
+                raise AuthenticationError("Invalid token")
+
 
             # Get user from database
-            user = db.query(User).filter(User.id == user_id).first()
+            user: User | None = crud_user.get(db, id=UUID(str(user_id)))
+
             if not user or not user.is_active:
                 raise TokenInvalidError("Invalid user or inactive account")
 
+            user: User
             # Generate new tokens
             return AuthService.create_tokens(user)
 
@@ -178,7 +181,7 @@ class AuthService:
         Raises:
             AuthenticationError: If current password is incorrect
         """
-        user = db.query(User).filter(User.id == user_id).first()
+        user = crud_user.get(db, id=user_id)
         if not user:
             raise AuthenticationError("User not found")
 
diff --git a/backend/tests/services/test_auth_service.py b/backend/tests/services/test_auth_service.py
index b043a3c..b339475 100644
--- a/backend/tests/services/test_auth_service.py
+++ b/backend/tests/services/test_auth_service.py
@@ -32,13 +32,14 @@ class TestAuthServiceAuthentication:
 
     def test_authenticate_nonexistent_user(self, db_session):
         """Test authenticating with an email that doesn't exist"""
-        user = AuthService.authenticate_user(
-            db=db_session,
-            email="nonexistent@example.com",
-            password="password"
-        )
+        with pytest.raises(AuthenticationError):
+            user = AuthService.authenticate_user(
+                db=db_session,
+                email="nonexistent@example.com",
+                password="password"
+            )
 
-        assert user is None
+            assert user is None
 
     def test_authenticate_with_wrong_password(self, db_session, mock_user):
         """Test authenticating with the wrong password"""
@@ -48,13 +49,14 @@ class TestAuthServiceAuthentication:
         db_session.commit()
 
         # Authenticate with wrong password
-        user = AuthService.authenticate_user(
-            db=db_session,
-            email=mock_user.email,
-            password="WrongPassword123"
-        )
+        with pytest.raises(AuthenticationError):
+            user = AuthService.authenticate_user(
+                db=db_session,
+                email=mock_user.email,
+                password="WrongPassword123"
+            )
 
-        assert user is None
+            assert user is None
 
     def test_authenticate_inactive_user(self, db_session, mock_user):
         """Test authenticating an inactive user"""