The records of 48 who underwent ASD closure at the Philippine Heart Center (PHC) over a 3-year period from July 1991 to June 1994 were reviewed. None of these patients had complex congenital heart disease nor did they have severe pulmonary hypertension. Of the 48 patients, 30 (63%) had an anterior mitral valve prolapse (MVP), while 26 patients (54%) had a mitral regurgitation (MR). The etiology of the MR varied with 17 patients having a MR due to the MVP, 3 patients due to a MVP associated with a cleft and?/or redundant anterior mitral valve (MV) leaflet, 1 patient due to rheumatic heart disease and 5 patients with no apparent cause of replacement. Of the 26 patients, 3 patients had a MV repair and1 patient had a MV replacement. Of the 26 patients wih MVP who had ASD closure without MV surgery, the MVP persisted in 18 patients (69%) in the immediate post-operative period. There were 8 patients with MVP associated with a mild to moderate MR who had ASD closure without MV surgery. Post-operatively, 6 patients (75%) had no more MR but the MVP was abolished in only 3 patients (38%). It is included that during the immediate post-operative period, ASD closure improves the MR anapparently the degree of MVP.