Balloon dilatation of calcified aortic stenosis was attempted in 12 patients, 6 men and 6 women, aged 38-82 years. Two patients underwent emergency surgery because of myocardial injury or pericardial tamponade. One patient with severe depressed left ventricular function in whom the procedure was attempted in cardiogenic shock died during the procedure. One patient experienced severe aortic insufficiency after dilatation. The remaining pressure gradient was higher than 50 mm Hg in another patient. Seven dilatations were considered to be successful with a remaining pressure gradient below 50 mm Hg and a mean gradient reduction of 53 mm Hg. In one of these 7 patients, who suffered from severe heart failure, valvoplasty had been carried out to make aortic valve replacement possible. The operation was performed 2 weeks later without complications. Five of 6 patients treated medically after successful valvoplasty had restenosis within 3 to 12 months. One of them exhibited a good result at 3 months but severe restenosis after one year. It is concluded that balloon valvoplasty of calcified aortic stenosis cannot be considered an alternative to surgery. If, however, left ventricular function improves after successful valvoplasty, valve replacement will then carry less risk.