From August, 1986 to December, 1993, mitral valve replacement was performed in 178 patients. Of the valve implanted, 114 were St.Jude Medical, 47 Duromedics, 16 Carpenter-Edward and 1 Ionesc-Shiley. The hospital mortality rate was 2.8%[5 patients and the late mortality rate was 7.5%[13 patients . The causes of hospital death were LV rupture in 1, renal failure in 1, cardiac tamponade in 1, valve malfunction in 1 and hypoxic brain damage in 1. The causes of late death were sudden death in 6, congestive heart failure in 4, brain ischemic injury in 3. Follow-up was done on 155 surviving patients : mean follow-up period was 50.94$pm$8.04 months. The actual survival rate was 88.2% at 8 years. We concluded, therefore, that good clinical results could be achieved with mitral valve replacement in mid-term follow-up, and long-term follow-up is also necessary.