Interfacial　fatigue　strength　has　been　suggested　as　a　measure　to　evaluate　the　bonding　strength　between　thin　hard　film　and　substrate.　Under　a　cyclic　loading　state,　debonding　occurs　in　the　elastic　regime,　the　plasticity　of　the　substrate　can　be　neglected　and　the　shear　stress　range　which　is　the　governing　stress　component　for　exfoliation　can　be　calculated　in　an　accurate　way.　However,　the　fatigue　test　using　an　Amsler-type　wear　machine　with　cylindrical　specimen　is　time　consuming　and　stress　concentration　at　the　edge　cannot　be　avoided.　In　this　study,　a　self-designed　rolling　contact　machine　is　used　and　the　film　is　coated　on　a　flat　surface,　on　which　a　series　of　bearing　balls　rotate　under　a　normal　load.　TiN　or　TiCN　films　were　coated　by　the　PCVD　or　IBED　methods.　The　results　show　that　the　interfacial　contact　fatigue　data　for　both　spherical　and　cylindrical　rolling　are　consistent　and　the　stress　concentration　factor　at　the　edge　of　the　cylinder　is　about　1.8-2.0.　Using　a　number　of　balls　the　testing　time　can　be　reduced.　(C)　1997　Elsevier　Science　S.A.