diff --git a/.gitignore b/.gitignore
index 14313d8..0ac5a8b 100644
--- a/.gitignore
+++ b/.gitignore
@@ -6,6 +6,7 @@
 
 # Packages
 *.egg
+*.eggs
 *.egg-info
 dist
 build
diff --git a/jsonmodels/fields.py b/jsonmodels/fields.py
index e900611..6d1a8f0 100644
--- a/jsonmodels/fields.py
+++ b/jsonmodels/fields.py
@@ -5,7 +5,7 @@
 import re
 import six
 from dateutil.parser import parse
-from typing import List, Optional, Dict, Set
+from typing import List, Optional, Dict, Set, Union, Pattern
 
 from .collections import ModelCollection
 from .errors import RequiredFieldError, BadTypeError, AmbiguousTypeError
@@ -14,6 +14,12 @@
 # it is a completely valid default value.
 NotSet = object()
 
+# BSON compatible types, which can be returned by toBsonEncodable.
+BsonEncodable = Union[
+    float, str, object, Dict, List, bytes, bool, datetime.datetime, None,
+    Pattern, int, bytes
+]
+
 
 class BaseField(object):
 
@@ -125,8 +131,26 @@ def _get_embed_type(value, models):
             return matching_models[0]
         return models[0]
 
+    def toBsonEncodable(self, value: types) -> BsonEncodable:
+        """Optionally return a bson encodable python object.
+
+        Returned object should be BSON compatible. By default uses the
+        `to_struct` method, which creates JSON compatible types. JSON is
+        compatible with bson, but only has support for limited types. When
+        required, this method should cast the value to supported bson type.
+        See: https://api.mongodb.com/python/current/api/bson/index.html
+
+        For example: when a value is a datetime object return it as a datetime
+        object. When a value is of CustomDateObject, cast it to a datetime
+        object before returning it.
+
+        :param value: Value
+        :return: a value which should be bson encodable
+        """
+        return self.to_struct(value=value)
+
     def to_struct(self, value):
-        """Cast value to Python structure."""
+        """Cast value to Python dict."""
         return value
 
     def parse_value(self, value):
diff --git a/tests/test_plain.py b/tests/test_plain.py
new file mode 100644
index 0000000..5736409
--- /dev/null
+++ b/tests/test_plain.py
@@ -0,0 +1,11 @@
+from unittest import mock
+
+from jsonmodels import fields
+
+
+@mock.patch('jsonmodels.fields.BaseField.to_struct')
+def test_toBsonEncodable_calls_to_struct(f):
+    """Test if default implementation of toBsonEncodable calls to_struct."""
+    field = fields.StringField()
+    field.toBsonEncodable(value="text")
+    f.assert_called_once()