We studied 203 patients with mitral stenosis treated by transarterial valvuloplasty. Forty two (group A) had undergone closed (n = 30) or open n = 12) surgical commissurotomy 15 ± 5 years before. The remaining 161 had not undergone previous surgery (group B). There were no significant differences between both groups in terms of age, sex, functional class, left atrial size, two-dimensional anatomic features of the valve, incidence of mild basal mitral regurgitation, or ejection fraction. A comparative analysis of both groups showed no significant differences in terms of changes in the mean gradient, mitral valve area, and incidence of severe postvalvuloplasty mitral regurgitation (9.5% versus 5.5%). Echo-Doppler follow-up studies (11 ± 7 months) showed persistent gradient relief in either group. We conclude that the immediate and short-term results of balloon valvuloplasty in patients who had undergone previous surgery are similar to those observed in patients who had not had commissurotomy. © 1990.