The Importance of Posterior Leaflet Preservation During Mitral Valve Replacement In this study, we attempted to investigate the importance of posterior leaflet preservation during mitral valve replacement (MVR). randomly selected patients with isolated mitral insufficiency were studied, 15 of those had MVR with preservation of the poster leaflet (group I), whereas in the other conventional MVR was performed without preservation of the posterior leaflet (group Ventricular functions of the patients were studied by using the echocardiographic examinations and nuclear scintigraphic methods, preoperatively and postoperatively 15 th days. The characteristics of both groups including age, aortic cross clamp time c preoperatively ejection fraction values were similar There were no in hospital deaths. During the postoperative period, ventricu function and functional capacity according to the New York Heart Association classification (NYHA) increased in the Grou patients. And this was greater than those of Group II. In the 3-18 months (mean 12 months) follow-up in group II only one patı was died. , As a result, we thought that this is a better technique than conventional MVR since the preservation of posterior leaflet, chon tendinae andpapiller muscles causes an increasing left ventricular performance.