Percutaneous transvenous mitral commissurotomy using the Inoue technique was performed in 390 cases of rheumatic mitral stenosis. There were 220 (56%) females and 170 (44%) males. The age range was 9-47 years [mean +/- S.D., 26 +/- 14) and all were symptomatic (New York Heart Association (NYHA) class II in 23 (6%); class III in 280 (72%); and class IV in 87 (22%) patients]. Mitral valve area increased from 0.6 +/- 0.4 to 2 +/- 0.7 cm2, mean transmitral gradients decreased from 26 +/- 8 to 5 +/- 3 mmHg and cardiac index improved from 2.2 +/- 0.8 to 3.0 +/- 0.7 l/min/m2 (P < 0.001). There were no procedure related deaths. An increase in mitral regurgitation by one grade was observed in 40 (10%) cases, with 8 (2%) cases developing severe mitral regurgitation. Oximetry evidence of left to right atrial shunt (Qp/Qs > or = 1.5:1) was observed in 11 (3%) patients. Four (1.0%) patients developed cardiac tamponade, none had thromboembolism. Follow-up of 290 cases at 26 +/- 5 weeks showed persistent improvement in clinical (NYHA class I in 98%) and echocardiographic mitral valve area. Percutaneous transvenous mitral commissurotomy is safe, easy to perform and provides excellent clinical and hemodynamic benefit in the majority of cases.