diff --git a/library/STMContainers/Multimap.hs b/library/STMContainers/Multimap.hs
--- a/library/STMContainers/Multimap.hs
+++ b/library/STMContainers/Multimap.hs
@@ -12,6 +12,7 @@
   focus,
   null,
   stream,
+  streamKeys,
   streamByKey,
 )
 where
@@ -148,6 +149,12 @@
 stream :: Multimap k v -> ListT STM (k, v)
 stream (Multimap m) = 
   Map.stream m >>= \(k, s) -> (k,) <$> Set.stream s
+
+-- |
+-- Stream keys.
+streamKeys :: Multimap k v -> ListT STM k
+streamKeys (Multimap m) =
+  fmap fst $ Map.stream m
 
 -- |
 -- Stream values by a key.
diff --git a/stm-containers.cabal b/stm-containers.cabal
--- a/stm-containers.cabal
+++ b/stm-containers.cabal
@@ -1,7 +1,7 @@
 name:
   stm-containers
 version:
-  0.2.5
+  0.2.6
 synopsis:
   Containers for STM
 description: