Background Left ventricular dysfunction is one of the important prognostic factors of early mortality and long-term survival after valve operation. We studied the intermediate term results of mitral valve reconstruction in patients with moderate to severe left ventricular dysfunction. Material and Method Forty four patients who underwent mitral valve reconstruction with a left ventricular ejection fraction (EF) of < 45% or less(20-45%) from April 1995 through July 2001 were reviewed retrospectively. Ages ranged from 10 to 67 years (46짹14 years) and 32 patients were in NYHA class III-IV. The mitral valve diseases were regurgitation(MR) in 28 patients, stenosis(MS) in 10, and mixed lesion in 5. The etiologies of mitral valve disease were rheumatic in 20 patients, degenerative in 14, ischemic in 5, annular dilatation in 2, congenital in 2, and endocarditis in 1. Operatively, all patients had annuloplasty and/or various valvuloplasty techniques, and a total of 52 procedures were concomitantly performed. Total cardiopulmonary bypass and aortic crossclamp time were 160짹57 minutes and 112짹45 minutes respectively. Result Two operative deaths occurred as a result of left ventricular failure(4.5%). After the mean follow-up of 39 months(range, 10-83 months), there was no late death. Transthoracic echocardiography revealed no or grade I of MR in 29 patients(29/40, 72.5%) and no or mild MS in 35 patients(35/40, 87.5%). The actuarial survival at 5 years was 100%. Four patients required mitral valve replacement due to progressive mitral valvular disease. The actuarial freedom from valve-related reoperation at 5 years was 84짹9%. Conclusion This study suggests that mitral valve reconstruction in patients with moderate to severe left ventricular dysfunction offers good early and intermediate survival and acceptable freedom from valve-related reoperation, and it is the strategy for effective management for these patients.