diff --git a/Network/HTTP/Date.hs b/Network/HTTP/Date.hs
--- a/Network/HTTP/Date.hs
+++ b/Network/HTTP/Date.hs
@@ -2,11 +2,11 @@
   Fast parser and formatter for HTTP Date.
 -}
 module Network.HTTP.Date (
-    module Network.HTTP.Date.Types
+    module Network.HTTP.Date.Converter
+  , module Network.HTTP.Date.Types
   -- * Utility functions
   , parseHTTPDate
   , formatHTTPDate
-  , epochTimeToHTTPDate
   ) where
 
 import Network.HTTP.Date.Converter
diff --git a/Network/HTTP/Date/Converter.hs b/Network/HTTP/Date/Converter.hs
--- a/Network/HTTP/Date/Converter.hs
+++ b/Network/HTTP/Date/Converter.hs
@@ -1,8 +1,13 @@
 {-# LANGUAGE BangPatterns #-}
-module Network.HTTP.Date.Converter (epochTimeToHTTPDate) where
+module Network.HTTP.Date.Converter ( epochTimeToHTTPDate
+                                   , httpDateToUTC
+                                   , utcToHTTPDate
+                                   ) where
 
 import Control.Applicative
 import Data.ByteString.Internal
+import Data.Time
+import Data.Time.Calendar.WeekDate
 import Data.Word
 import Foreign.Marshal.Array
 import Foreign.Ptr
@@ -34,6 +39,40 @@
     w = (days + 3) `rem` 7 + 1
     (y,m,d) = toYYMMDD days
     (h,n,s) = toHHMMSS secs
+
+-- | Translating 'HTTPDate' to 'UTCTime'.
+--
+--   Since 0.0.7.
+httpDateToUTC :: HTTPDate -> UTCTime
+httpDateToUTC x = UTCTime (fromGregorian y m d) (secondsToDiffTime s)
+  where
+    y = fromIntegral $ hdYear x
+    m = hdMonth x
+    d = hdDay x
+    s = fromIntegral $ (hdHour   x `rem` 24) * 3600
+                     + (hdMinute x `rem` 60) * 60
+                     + (hdSecond x `rem` 60)
+
+-- | Translating 'UTCTime' to 'HTTPDate'.
+--
+--   Since 0.0.7.
+utcToHTTPDate :: UTCTime -> HTTPDate
+utcToHTTPDate x = defaultHTTPDate {
+    hdYear   = fromIntegral y
+  , hdMonth  = m
+  , hdDay    = d
+  , hdHour   = h
+  , hdMinute = n
+  , hdSecond = round s
+  , hdWkday  = fromEnum (w :: Int)
+  }
+  where
+    (y, m, d) = toGregorian day
+    (h, n, s) = ((todHour tod), (todMin tod), (todSec tod))
+    (_, _, w) = toWeekDate day
+    day       = localDay time
+    tod       = localTimeOfDay time
+    time      = utcToLocalTime utc x
 
 toYYMMDD :: Int -> (Int,Int,Int)
 toYYMMDD x = (yy, mm, dd)
diff --git a/http-date.cabal b/http-date.cabal
--- a/http-date.cabal
+++ b/http-date.cabal
@@ -1,5 +1,5 @@
 Name:                   http-date
-Version:                0.0.6.1
+Version:                0.0.7
 Author:                 Kazu Yamamoto <kazu@iij.ad.jp>
 Maintainer:             Kazu Yamamoto <kazu@iij.ad.jp>
 License:                BSD3
@@ -21,6 +21,7 @@
                       , array
                       , attoparsec
                       , bytestring
+                      , time
 
 Test-Suite spec
   Type:                 exitcode-stdio-1.0
diff --git a/test/DateSpec.hs b/test/DateSpec.hs
--- a/test/DateSpec.hs
+++ b/test/DateSpec.hs
@@ -9,7 +9,7 @@
 
 spec :: Spec
 spec = do
-    describe "formatHTTPDat" $ do
+    describe "formatHTTPDate" $ do
         it "behaves like the model" $ 
             forM_ [0,100000..10000000000] $ \epochtime -> do
                 let m = model epochtime
@@ -17,9 +17,21 @@
                     model = utcToDate . epochTimeToUtcTime
                     ours  = formatHTTPDate . epochTimeToHTTPDate
                 o `shouldBe` m
-    describe "parseHTTPDate" $ do
+    describe "httpDateToUTC" $ do
         it "behaves like the model" $ 
             forM_ [0,100000..10000000000] $ \epochtime -> do
+                let m = epochTimeToUtcTime epochtime
+                    o = httpDateToUTC $ epochTimeToHTTPDate epochtime
+                o `shouldBe` m
+    describe "parseHTTPDate" $ do
+        it "behaves like the model" $
+            forM_ [0,100000..10000000000] $ \epochtime -> do
                 let m = epochTimeToHTTPDate epochtime
                     Just o = parseHTTPDate $ formatHTTPDate m
+                o `shouldBe` m
+    describe "utcToHTTPDate" $ do
+        it "behaves like the model" $
+            forM_ [0,100000..10000000000] $ \epochtime -> do
+                let m = epochTimeToHTTPDate epochtime
+                    o = utcToHTTPDate $ epochTimeToUtcTime epochtime
                 o `shouldBe` m