Percutaneous transfemoral valvuloplasty was performed in 20 patients (aged 25-83 years; mean 62) with marked signs of aortic valve stenosis, some calcified, others noncalcified. The transvalvar systolic pressure gradient was reduced from a mean of 104 +/- 7 mm Hg to a mean of 46 +/- 4 mm Hg, the valvar opening area from 0.38 +/- 0.04 cm2 to 0.74 +/- 0.04 cm2. The result was judged to be unsatisfactory in four patients and required aortic valve replacement after initially good results from the balloon dilatation. Serious complications were reversible ventricular fibrillation and reversible cerebral ischemia with partial hemiparesis in one patient each. In three patients the femoral artery had to be repaired at the site of puncture, twice the balloon ruptured without sequelae, once reversible pericardial effusion occurred, and twice there were reactions to antibiotics given after the procedure. Invasive re-catheterizations were performed in four patients, at intervals of three months: no increase in pressure gradient was observed. The results indicate that reduction of the transvalvar pressure gradient by 40 mm Hg can produce rapid reversal of heart failure and a symptom-free state even in patients who were already decompensated.