Objective Report long term results of patients operated of mitral valve replacement (MVR) for isolated chronic mitral insufficiency associated with severely enlarged left ventricle(LV).Methods Between April 1988 and September 2000, 45 patients(28 male and 17 female) with a mean age of (33.8±10.5) years(range:13-58 yrs), underwent MVR at Anzhen Hospital.Cases collected condition: All patients had aseverly mitral valve regigutation(MR) with LV Diastole Diameter(LVDD)>70mm.MR was rheumatic in origin in 36 cases(80%) and congenital in 9 cases(20%).13 cases were in NYHA functional class Ⅱ and 32 cases in class Ⅲ-Ⅳ.At X-ray, the C/T was 0.64±0.12 (range:0.47-0.84).Echocardiogram(UCG) showed severe MR and LV hypertrophy in all patients: LVDD was (76.3±4.1)mm(range:70.2-89.6mm).Ejective fraction(EF) was (45.7±6.3)%(Range: 30.0%-66.3 %).Mitral valve replacementwas performed in all patients under hypothermic cardio-pulmonary by-pass.Result Two out of 45 cases died in the perioperative period accounting for a mortalityrate of 4.4%.Two weeks after surgery the echocardiogram showed a reduction of LVDD [from (76.3±6.5) to (65±5.2)mm,P<0.01].Follow-up results: Follow-up was completed in 37 cases(82.2%).Mean follow up term was (13.8±0.12) years (144-264 months).21 cases were alive now with a ratio of 56.7% in 37 cases.5 out of 37 cases was class Ⅰ(NYHA), and 14 cases was class Ⅱ, 2 cases was class Ⅲ.12 cases were dead during follow-up with a ratio of 32.4%, 4 cases were out of correspondence with a ratio of 5.4%.9 cases out of all deaths were due to cardiac events with a ratio of 75%, the main cardic events were including anti-congnition complication and chronic cardiac failure or kidny failure.All alives were with LVDD further decreased at late control[from(76.3±6.5) to(60.0±6.1)mm, P<0.001).Conclusion Mitral valve replacement is indicated in patients with mitral insufficiency and very dilated left ventricles, and the intervention has the potential to reduce LV severe dilation and in some cases to revert to normal.Anti-congnition and chronic heart failur were main reasons of late death.