diff --git a/lms/djangoapps/course_api/serializers.py b/lms/djangoapps/course_api/serializers.py
index adcf578e7488..d9188a51c4eb 100644
--- a/lms/djangoapps/course_api/serializers.py
+++ b/lms/djangoapps/course_api/serializers.py
@@ -123,7 +123,7 @@ def get_hidden(self, course_overview):
         Represents whether course is hidden in LMS
         """
         catalog_visibility = course_overview.catalog_visibility
-        return catalog_visibility in ['about', 'none']
+        return catalog_visibility in ['about', 'none'] or course_overview.id.deprecated  # Old Mongo should be hidden
 
     def get_blocks_url(self, course_overview):
         """
diff --git a/lms/djangoapps/course_api/tests/test_serializers.py b/lms/djangoapps/course_api/tests/test_serializers.py
index b80cc6379985..7bba11d54055 100644
--- a/lms/djangoapps/course_api/tests/test_serializers.py
+++ b/lms/djangoapps/course_api/tests/test_serializers.py
@@ -78,7 +78,7 @@ def setUp(self):
             'effort': '6 hours',
             'pacing': 'instructor',
             'mobile_available': True,
-            'hidden': False,
+            'hidden': True,  # because it's an old mongo course
             'invitation_only': False,
 
             # 'course_id' is a deprecated field, please use 'id' instead.