diff --git a/mongoengine/fields.py b/mongoengine/fields.py
index 227af0a7..e4d95d53 100644
--- a/mongoengine/fields.py
+++ b/mongoengine/fields.py
@@ -22,9 +22,10 @@ class StringField(BaseField):
     """A unicode string field.
     """
 
-    def __init__(self, regex=None, max_length=None, **kwargs):
+    def __init__(self, regex=None, max_length=None, min_length=None, **kwargs):
         self.regex = re.compile(regex) if regex else None
         self.max_length = max_length
+        self.min_length = min_length
         super(StringField, self).__init__(**kwargs)
 
     def to_python(self, value):
@@ -35,6 +36,9 @@ class StringField(BaseField):
 
         if self.max_length is not None and len(value) > self.max_length:
             raise ValidationError('String value is too long')
+        
+        if self.min_length is not None and len(value) < self.min_length:
+            raise ValidationError('String value is too short')
 
         if self.regex is not None and self.regex.match(value) is None:
             message = 'String value did not match validation regex'