Mode　dependent　directional　transform　(MDDT)　can　improve　the　coding　efficiency　of　H.264/AVC　but　it　also　brings　high　computation　complexity.　In　this　paper　we　present　a　new　design　for　implementing　fast　MDDT　transform　through　integer　lifting　steps.　We　first　approximate　the　optimal　MDDT　by　a　proper　transform　matrix　that　can　be　implemented　with　butterfly-style　operation.　We　further　factorize　the　butterfly-style　transform　into　a　series　of　integer　lifting　steps　to　eliminate　the　need　of　multiplications.　Experimental　results　show　that　the　proposed　fast　MDDT　can　significantly　reduce　the　computation　complexity　while　introducing　negligible　loss　in　the　coding　efficiency.　Due　to　the　merit　of　integer　lifting　steps,　the　proposed　fast　MDDT　is　reversible　and　can　be　implemented　on　hardware　very　easily.　(C)　2011　Elsevier　Inc.　All　rights　reserved.