BACKGROUND: Mitral annular plane systolic excursion assessed by M mode echo is a validated parameter for indicating LV longitudinal function. Reduced MAPSE is mostly related to fibrosis in the context of rheumatic mitral stenosis. Our study is aimed at observing the effect of balloon mitral valvotomy on MAPSE in patients with isolated severe mitral stenosis METHODS: A total of 113 patients with mitral stenosis was screened and 30 patients according to inclusion criteria in all age groups with isolated rheumatic mitral stenosis in whom BMV was suitable were enrolled in the study. MAPSE was measured by M–mode images obtained at the LV septal, lateral, anterior, and posterior borders of the mitral ring in the apical 2–chamber and 4–chamber views, and an average MAPSE value was calculated. All the parameters were assessed before BMV and 2 weeks after procedure. RESULTS: Pre BMV,MAPSE was lower in patients with Subvalvular disease which was statistically significant. Paradoxically MAPSE was higher in patients with very severe stenosis and severe pulmonary hypertension but was not statistically significant. Post BMV, EF remained more or less the same but there was statistically significant improvement in MAPSE. Improvement in MAPSE was significantly less in group with subvalvular disease CONCLUSION: MAPSE can be useful in detecting early longitudinal dysfunction even in cases of preserved global LV function in severe mitral stenosis patients and shows a significant improvement after successful BMV