diff --git a/flask_mongorest/utils.py b/flask_mongorest/utils.py
index 272473d2..572c8643 100644
--- a/flask_mongorest/utils.py
+++ b/flask_mongorest/utils.py
@@ -1,3 +1,4 @@
+import enum
 import json
 import decimal
 import datetime
@@ -26,6 +27,8 @@ def default(self, value, **kwargs):
             return value.strftime("%Y-%m-%d")
         if isinstance(value, decimal.Decimal):
             return str(value)
+        if isinstance(value, enum.Enum):
+            return value.value
         return super(MongoEncoder, self).default(value, **kwargs)