Balloon mitral valvotomy (BMV) constitutes an important alternative to surgical closed mitral valvotomy (CMV) for the treatment of rheumatic mitral stenosis. To compare the immediate and long-term results of these procedures, 200 patients with rheumatic mitral stenosis were randomly assigned to undergo either BMV (n = 100) or CMV (n = 100). The age range was 10 to 30 (mean 19.4 +/- 6.5) years. Both procedures resulted in significant and similar increases in mitral valve area (BMV: 0.85 +/- 0.26 to 2.39 +/- 0.94 cm2; CMV: 0.79 +/- 0.21 to 2.2 +/- 0.85 cm2; p = NS). Mitral regurgitation developed in 14 patients after BMV and in 12 patients after CMV. Eighty patients in each group have now been followed for a mean period of 22 +/- 6.3 (range 6 to 38) months by repeat echocardiographic study. Restenosis (defined as a loss of more than 50% of the achieved increase in mitral valve area) was seen in four (5%) patients after BMV and in three (4%) after CMV. Symptomatic restenosis was seen in only one patient who at follow-up examination 20 months after CMV had a mitral valve area of 0.8 cm2 and underwent successful balloon valvotomy. We conclude that the immediate and long-term results obtained with percutaneous BMV and surgical closed mitral commissurotomy are comparable.