Percutaneous double balloon valvotomy for severe rheumatic mitral stenosis was successfully performed in 281 of 285 consecutive patients. The changes evoked were a decrease of the mean transvalvular gradient from 16 +/- 7 to 5 +/- 3 mm Hg, an increase in cardiac output from 3.8 +/- 1.0 liters/min to 5.4 +/- 1.5 liters/min and an increase in mitral valve area from 0.86 +/- 0.24 cm2 to 2.41 +/- 0.54 cm2. The mean pulmonary artery pressure decreased from 37 +/- 13 mm Hg to 27 +/- 12 mm Hg and the pulmonary vascular resistance decreased from 307 +/- 181 to 238 +/- 122 dynes/s/cm-5. Symptomatic improvement occurred in 272 of the 285 (95%) patients. There were 3 procedure-related deaths (1%). Postdilatation mitral regurgitation was not significant in most patients. Therefore, this procedure can be performed at a low risk with effective results and a fast recovery.