diff --git a/CHANGELOG b/CHANGELOG
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,3 +1,7 @@
+1.2.1.0
+
+*  Add traverse
+
 1.2.0.11
 
 *  Dropped upper version bounds of dependencies because it's to much work to maintain.
diff --git a/Data/CaseInsensitive.hs b/Data/CaseInsensitive.hs
--- a/Data/CaseInsensitive.hs
+++ b/Data/CaseInsensitive.hs
@@ -28,6 +28,7 @@
                             , original
                             , foldedCase
                             , map
+                            , traverse
                             , FoldCase(foldCase)
                             ) where
 import Data.CaseInsensitive.Internal
diff --git a/Data/CaseInsensitive/Internal.hs b/Data/CaseInsensitive/Internal.hs
--- a/Data/CaseInsensitive/Internal.hs
+++ b/Data/CaseInsensitive/Internal.hs
@@ -22,6 +22,7 @@
                                      , original
                                      , foldedCase
                                      , map
+                                     , traverse
                                      , FoldCase(foldCase)
                                      ) where
 
@@ -30,6 +31,7 @@
 --------------------------------------------------------------------------------
 
 -- from base:
+import Control.Applicative (Applicative)
 import Data.Bool      ( (||) )
 import Data.Char      ( Char, toLower )
 import Data.Eq        ( Eq, (==) )
@@ -106,6 +108,10 @@
 -- | Transform the original string-like value but keep it case insensitive.
 map :: FoldCase s2 => (s1 -> s2) -> (CI s1 -> CI s2)
 map f = mk . f . original
+
+-- | Transform the original string-like value but keep it case insensitive.
+traverse :: (FoldCase s2, Applicative f) => (s1 -> f s2) -> CI s1 -> f (CI s2)
+traverse f = fmap mk . f . original
 
 instance (IsString s, FoldCase s) => IsString (CI s) where
     fromString = mk . fromString
diff --git a/case-insensitive.cabal b/case-insensitive.cabal
--- a/case-insensitive.cabal
+++ b/case-insensitive.cabal
@@ -1,5 +1,5 @@
 name:          case-insensitive
-version:       1.2.0.11
+version:       1.2.1.0
 cabal-version: >=1.8
 build-type:    Simple
 license:       BSD3