The　finite-element　method　(FEM)　has　become　an　applicable　method　to　analyse　the　stress　distribution　of　bioprosthetic　valves.　However,　most　of　the　stress　analyses　performed　in　the　past　have　been　oil　bioprosthetic　aortic　valves.　No　public　reports　are　available　oil　the　numerical　simulation　of　stress　analysis　for　stentless　quadrileaflet　pericardial　mitral　valves　up　to　date.　This　study　applied　FEM　to　investigate　the　mechanical　behaviours　of　a　modified　stentless　quadrileaflet　pericardial　mitral　valve.　The　finite-element　model　includes　the　material　non-linearity,　large　deformation　and　the　contact　condition　of　leaflets.　The　results　showed　that　the　deformed　shapes　of　valve　in　the　numerical　simulation　are　quite　similar　to　ones　observed　in　the　hydrodynamic　experiment　in　vitro,　the　stress　distribution　is　relatively　uniform　and　the　magnitudes　of　stresses　are　in　a　reasonable　range.　It　call　be　concluded　that　the　finite-element　model　in　this　paper　is　reasonable　and　feasible,　and　the　numerical　results　can　be　used　to　evaluate　the　biomechanical　performance　of　this　valve.　Copyright　(c)　2007　John　Wiley　&　Sons,　Ltd.