OBJECTIVE We determined factors associated with long-term outcomes of patients who underwent successful percutaneous mitral balloon valvuloplasty (PMV). METHODS Between August 1980 and May 2013, 1187 patients underwent PMV at Severance Hospital, Seoul, Korea. A total of 742 patients who underwent regular clinic visits for more than 10 years were retrospectively analyzed. The endpoints consisted of repeated PMV, mitral valve (MV) surgery, and cardiovascular-related death. RESULTS The optimal result, defined as a post-PMV mitral valve area (MVA) >1.5 cm² and mitral regurgitation ≤Grade II, was obtained in 631 (85%) patients. Over a mean follow up duration of 214±50 months, 54 (7.3%) patients underwent repeat PMV, 4 (0.5%) underwent trido-PMV, and 248 (33.4%) underwent MV surgery. A total of 33 patients (4.4%) had stroke, and 35 (4.7%) patients died from cardiovascular-related reasons. In a multivariate analysis, echocardiographic score [p=0.003, hazard ratio=1.56, 95% confidence interval (CI): 1.01-2.41] and post-MVA cut-off (p<0.001, relative risk=0.39, 95% CI: 0.37-0.69) were the only significant predictors of long-term clinical outcomes after adjusting for confounding variables. A post-MVA cut-off value of 1.76 cm² showed satisfactory predictive power for poor long-term clinical outcomes. CONCLUSIONS In this long-term follow up study (up to 20 years), an echocardiographic score >8 and post-MVA ≤1.76 cm² were independent predictors of poor long-term clinical outcomes after PMV, including MV reintervention, stroke, and cardiovascular-related death.