diff --git a/rest_auth/serializers.py b/rest_auth/serializers.py
index a2d1a82..5bf1ac2 100644
--- a/rest_auth/serializers.py
+++ b/rest_auth/serializers.py
@@ -50,11 +50,18 @@ class LoginSerializer(serializers.Serializer):
                     msg = _('Must include either "username" or "email" and "password".')
                     raise exceptions.ValidationError(msg)
 
-        elif username and password:
-            user = authenticate(username=username, password=password)
+        elif username or email and password:
+            # Try get username if we have in request email
+            if email and not username:
+                try:
+                    username = UserModel.objects.get(email__iexact=email).username
+                except UserModel.DoesNotExist:
+                    user = None
+            if username:
+                user = authenticate(username=username, password=password)
 
         else:
-            msg = _('Must include "username" and "password".')
+            msg = _('Must include either "username" or "email" and "password".')
             raise exceptions.ValidationError(msg)
 
         # Did we get back an active user?
diff --git a/rest_auth/tests/test_api.py b/rest_auth/tests/test_api.py
index bb15e01..0cf55a2 100644
--- a/rest_auth/tests/test_api.py
+++ b/rest_auth/tests/test_api.py
@@ -2,6 +2,7 @@ from django.core.urlresolvers import reverse
 from django.test import TestCase
 from django.contrib.auth import get_user_model
 from django.core import mail
+from django.conf import settings
 from django.test.utils import override_settings
 from django.utils.encoding import force_text
 
@@ -90,6 +91,51 @@ class APITestCase1(TestCase, BaseAPITestCase):
         # test empty payload
         self.post(self.login_url, data={}, status_code=400)
 
+    def test_login_by_email(self):
+        # starting test without allauth app
+        settings.INSTALLED_APPS.remove('allauth')
+
+        payload = {
+            "email": self.EMAIL.lower(),
+            "password": self.PASS
+        }
+        # there is no users in db so it should throw error (400)
+        self.post(self.login_url, data=payload, status_code=400)
+
+        self.post(self.password_change_url, status_code=403)
+
+        # create user
+        user = get_user_model().objects.create_user(self.USERNAME, self.EMAIL, self.PASS)
+
+        # test auth by email
+        self.post(self.login_url, data=payload, status_code=200)
+        self.assertEqual('key' in self.response.json.keys(), True)
+        self.token = self.response.json['key']
+
+        # test auth by email in different case
+        payload = {
+            "email": self.EMAIL.upper(),
+            "password": self.PASS
+        }
+        self.post(self.login_url, data=payload, status_code=200)
+        self.assertEqual('key' in self.response.json.keys(), True)
+        self.token = self.response.json['key']
+
+        # test inactive user
+        user.is_active = False
+        user.save()
+        self.post(self.login_url, data=payload, status_code=400)
+
+        # test wrong email/password
+        payload = {
+            "email": 't' + self.EMAIL,
+            "password": self.PASS
+        }
+        self.post(self.login_url, data=payload, status_code=400)
+
+        # test empty payload
+        self.post(self.login_url, data={}, status_code=400)
+
     def test_password_change(self):
         login_payload = {
             "username": self.USERNAME,