Objective A nonlinear finite element model was used for comparing stentless? pericardial mitral valve and stented? pericardial three-leaflet valve to identify their static stress distribution at valve open and closed position during cardiac cycle. Methods A finite element code was developed? by using the 8-node super-parameter nonlinear shells and the Newton-Raphson method. The load was the mean transvalvular? pressure gradient of the tested valves at open and closed position, and the stress was determined. Results At an internal pressure of l20mmHg in mitral valve closed position, stentless? pericardial mitral valve showed more reasonable stress distribution than that of stented? pericardial three-leaflet valve. The maximum first principle normal stress, of which the area corresponded with the perforation point, was 2.352MPa in stented pericardial three-leaflet valve. The average first principle normal stress of stented pericardial three-leaflet valve (0.223~0.724MPa) was higher than that of stentless pericardial mitral valve (0.040~0.l49Mpa). Conclusion A finite element analysis of the quadrileaflet? stentless mitral valve, whose geometry and action was nonlinear, was effective and feasible. It shows that for the stentless pericardial mitral valve, the absence of the stent resulted in reduced stress on the leaflets. It could bepostulated that this will lead to a decrease of tears, perforation and calcification, which may result in an improved long-term behavior.