diff --git a/mongodbatlas/project_api_key.go b/mongodbatlas/project_api_key.go
index a3840a942..f3322bae3 100644
--- a/mongodbatlas/project_api_key.go
+++ b/mongodbatlas/project_api_key.go
@@ -14,7 +14,7 @@ const projectAPIKeysPath = "groups/%s/apiKeys"
 type ProjectAPIKeysService interface {
 	List(context.Context, string, *ListOptions) ([]APIKey, *Response, error)
 	Create(context.Context, string, *APIKeyInput) (*APIKey, *Response, error)
-	Assign(context.Context, string, string) (*Response, error)
+	Assign(context.Context, string, string, *AssignAPIKey) (*Response, error)
 	Unassign(context.Context, string, string) (*Response, error)
 }
 
@@ -26,6 +26,11 @@ type ProjectAPIKeysOp struct {
 
 var _ ProjectAPIKeysService = &ProjectAPIKeysOp{}
 
+// AssignAPIKey contains the roles to be assigned to an Organization API key into a Project
+type AssignAPIKey struct {
+	Roles []string `json:"roles"`
+}
+
 //List all API-KEY in the organization associated to {GROUP-ID}.
 //See more: https://docs.atlas.mongodb.com/reference/api/projectApiKeys/get-all-apiKeys-in-one-project/
 func (s *ProjectAPIKeysOp) List(ctx context.Context, groupID string, listOptions *ListOptions) ([]APIKey, *Response, error) {
@@ -80,9 +85,9 @@ func (s *ProjectAPIKeysOp) Create(ctx context.Context, groupID string, createReq
 
 //Assign an API-KEY related to {GROUP-ID} to a the project with {API-KEY-ID}.
 //See more: https://docs.atlas.mongodb.com/reference/api/projectApiKeys/assign-one-org-apiKey-to-one-project/
-func (s *ProjectAPIKeysOp) Assign(ctx context.Context, groupID string, keyID string) (*Response, error) {
+func (s *ProjectAPIKeysOp) Assign(ctx context.Context, groupID string, keyID string, assignAPIKeyRequest *AssignAPIKey) (*Response, error) {
 	if groupID == "" {
-		return nil, NewArgError("apiKeyID", "must be set")
+		return nil, NewArgError("groupID", "must be set")
 	}
 
 	if keyID == "" {
@@ -93,7 +98,7 @@ func (s *ProjectAPIKeysOp) Assign(ctx context.Context, groupID string, keyID str
 
 	path := fmt.Sprintf("%s/%s", basePath, keyID)
 
-	req, err := s.client.NewRequest(ctx, http.MethodPost, path, nil)
+	req, err := s.client.NewRequest(ctx, http.MethodPatch, path, assignAPIKeyRequest)
 	if err != nil {
 		return nil, err
 	}
diff --git a/mongodbatlas/project_api_key_test.go b/mongodbatlas/project_api_key_test.go
index d57e35c60..e091a1e94 100644
--- a/mongodbatlas/project_api_key_test.go
+++ b/mongodbatlas/project_api_key_test.go
@@ -108,10 +108,10 @@ func TestProjectAPIKeys_Assign(t *testing.T) {
 	keyID := "5d1d12c087d9d63e6d682438"
 
 	mux.HandleFunc(fmt.Sprintf("/groups/%s/apiKeys/%s", groupID, keyID), func(w http.ResponseWriter, r *http.Request) {
-		testMethod(t, r, http.MethodPost)
+		testMethod(t, r, http.MethodPatch)
 	})
 
-	_, err := client.ProjectAPIKeys.Assign(ctx, groupID, keyID)
+	_, err := client.ProjectAPIKeys.Assign(ctx, groupID, keyID, &AssignAPIKey{})
 	if err != nil {
 		t.Errorf("ProjectAPIKeys.Assign returned error: %v", err)
 	}