diff --git a/CHANGELOG.markdown b/CHANGELOG.markdown
--- a/CHANGELOG.markdown
+++ b/CHANGELOG.markdown
@@ -1,3 +1,7 @@
+4.4
+---
+* Support `mmorph`
+
 4.3.4.1
 -------
 * Support `MonadRandom` 0.4
diff --git a/either.cabal b/either.cabal
--- a/either.cabal
+++ b/either.cabal
@@ -1,6 +1,6 @@
 name:          either
 category:      Control, Monads
-version:       4.3.4.1
+version:       4.4
 license:       BSD3
 cabal-version: >= 1.6
 license-file:  LICENSE
@@ -34,6 +34,7 @@
     monad-control     >= 0.3.2   && < 1.1,
     MonadRandom       >= 0.1     && < 0.5,
     mtl               >= 2.0     && < 2.3,
+    mmorph            >= 1.0.0   && < 1.0.4,
     profunctors       >= 4       && < 6,
     semigroups        >= 0.8.3.1 && < 1,
     semigroupoids     >= 4       && < 6,
diff --git a/src/Control/Monad/Trans/Either.hs b/src/Control/Monad/Trans/Either.hs
--- a/src/Control/Monad/Trans/Either.hs
+++ b/src/Control/Monad/Trans/Either.hs
@@ -7,6 +7,7 @@
 {-# LANGUAGE FlexibleContexts      #-}
 {-# LANGUAGE UndecidableInstances  #-}
 {-# LANGUAGE MultiParamTypeClasses #-}
+{-# LANGUAGE RankNTypes #-}
 {-# LANGUAGE TypeFamilies #-}
 -----------------------------------------------------------------------------
 -- |
@@ -49,6 +50,7 @@
 import Control.Monad.Trans.Control (MonadBaseControl(..), MonadTransControl(..), defaultLiftBaseWith, defaultRestoreM)
 import Control.Monad.Writer.Class
 import Control.Monad.Random (MonadRandom,getRandom,getRandoms,getRandomR,getRandomRs)
+import Control.Monad.Morph (MFunctor, hoist)
 import Data.Either.Combinators ( swapEither )
 import Data.Foldable
 import Data.Function (on)
@@ -92,6 +94,10 @@
   compare = compare `on` runEitherT
   {-# INLINE compare #-}
 
+instance MFunctor (EitherT e) where
+  hoist f = EitherT . f . runEitherT
+  {-# INLINE hoist #-}
+
 -- | Given a pair of actions, one to perform in case of failure, and one to perform
 -- in case of success, run an 'EitherT' and get back a monadic result.
 eitherT :: Monad m => (a -> m c) -> (b -> m c) -> EitherT a m b -> m c
@@ -343,7 +349,7 @@
   {-# INLINE liftWith #-}
   restoreT = EitherT . liftM unStEitherT
   {-# INLINE restoreT #-}
- 
+
 instance MonadBaseControl b m => MonadBaseControl b (EitherT e m) where
   newtype StM (EitherT e m) a = StMEitherT { unStMEitherT :: StM m (StT (EitherT e) a) }
   liftBaseWith = defaultLiftBaseWith StMEitherT