Balloon valvuloplasty is performed in the cardiac catheterization laboratory without general anesthesia. A balloon catheter is inserted percutaneously in the venous side of the circulation and is placed across the mitral valve after puncture of the atrial septum. Inflation of appropriately sized balloons has resulted in marked reduction of transvalvular gradients and increase in calculated valve area in most of the cases thus far reported. Given the success of closed commissurotomy, these are not surprising findings.