diff --git a/ChangeLog.md b/ChangeLog.md
--- a/ChangeLog.md
+++ b/ChangeLog.md
@@ -1,3 +1,7 @@
+## 1.2.11
+
+* Add `unfoldEither` and `unfoldEitherM` to `Data.Conduit.List`
+
 ## 1.2.10
 
 * Add `PrimMonad` instances for `ConduitM` and `Pipe`
diff --git a/Data/Conduit/Internal/List/Stream.hs b/Data/Conduit/Internal/List/Stream.hs
--- a/Data/Conduit/Internal/List/Stream.hs
+++ b/Data/Conduit/Internal/List/Stream.hs
@@ -23,6 +23,19 @@
             Just (x, s') -> Emit s' x
 {-# INLINE unfoldS #-}
 
+unfoldEitherS :: Monad m
+              => (b -> Either r (a, b))
+              -> b
+              -> StreamConduitM i a m r
+unfoldEitherS f s0 _ =
+    Stream step (return s0)
+  where
+    step s = return $
+        case f s of
+            Left r        -> Stop r
+            Right (x, s') -> Emit s' x
+{-# INLINE unfoldEitherS #-}
+
 unfoldMS :: Monad m
          => (b -> m (Maybe (a, b)))
          -> b
@@ -37,6 +50,19 @@
             Just (x, s') -> Emit s' x
 {-# INLINE unfoldMS #-}
 
+unfoldEitherMS :: Monad m
+         => (b -> m (Either r (a, b)))
+         -> b
+         -> StreamConduitM i a m r
+unfoldEitherMS f s0 _ =
+    Stream step (return s0)
+  where
+    step s = do
+        ms' <- f s
+        return $ case ms' of
+            Left r        -> Stop r
+            Right (x, s') -> Emit s' x
+{-# INLINE unfoldEitherMS #-}
 sourceListS :: Monad m => [a] -> StreamProducer m a
 sourceListS xs0 _ =
     Stream (return . step) (return xs0)
diff --git a/Data/Conduit/List.hs b/Data/Conduit/List.hs
--- a/Data/Conduit/List.hs
+++ b/Data/Conduit/List.hs
@@ -19,7 +19,9 @@
       sourceList
     , sourceNull
     , unfold
+    , unfoldEither
     , unfoldM
+    , unfoldEitherM
     , enumFromTo
     , iterate
     , replicate
@@ -73,6 +75,7 @@
 import Prelude
     ( ($), return, (==), (-), Int
     , (.), id, Maybe (..), Monad
+    , Either (..)
     , Bool (..)
     , (>>)
     , (>>=)
@@ -114,6 +117,25 @@
 {-# INLINE unfoldC #-}
 STREAMING(unfold, unfoldC, unfoldS, f x)
 
+-- | Generate a source from a seed value with a return value.
+--
+-- Subject to fusion
+--
+-- @since 1.2.11
+unfoldEither, unfoldEitherC :: Monad m
+                            => (b -> Either r (a, b))
+                            -> b
+                            -> ConduitM i a m r
+unfoldEitherC f =
+    go
+  where
+    go seed =
+        case f seed of
+            Right (a, seed') -> yield a >> go seed'
+            Left r -> return r
+{-# INLINE unfoldEitherC #-}
+STREAMING(unfoldEither, unfoldEitherC, unfoldEitherS, f x)
+
 -- | A monadic unfold.
 --
 -- Subject to fusion
@@ -132,6 +154,25 @@
             Just (a, seed') -> yield a >> go seed'
             Nothing -> return ()
 STREAMING(unfoldM, unfoldMC, unfoldMS, f seed)
+
+-- | A monadic unfoldEither.
+--
+-- Subject to fusion
+--
+-- @since 1.2.11
+unfoldEitherM, unfoldEitherMC :: Monad m
+                              => (b -> m (Either r (a, b)))
+                              -> b
+                              -> ConduitM i a m r
+unfoldEitherMC f =
+    go
+  where
+    go seed = do
+        mres <- lift $ f seed
+        case mres of
+            Right (a, seed') -> yield a >> go seed'
+            Left r -> return r
+STREAMING(unfoldEitherM, unfoldEitherMC, unfoldEitherMS, f seed)
 
 -- | Yield the values from the list.
 --
diff --git a/conduit.cabal b/conduit.cabal
--- a/conduit.cabal
+++ b/conduit.cabal
@@ -1,5 +1,5 @@
 Name:                conduit
-Version:             1.2.10
+Version:             1.2.11
 Synopsis:            Streaming data processing library.
 description:
     `conduit` is a solution to the streaming data problem, allowing for production,