Percutaneous balloon pulmonary valvuloplasty was performed in 17 consecutive patients, ranging in age from eleven years to 67 years (mean age: 40 +/- 17 years). The peak to peak pressure gradient was reduced by 16 to 167 mm Hg, the mean pressure gradient decreased from 99 +/- 42 to 46 +/- 22 mm Hg. In six patients there was a pressure gradient above 50 mm Hg after the procedure. Within three months it decreased due to regression of infundibular hypertrophy and ranged from 26 to 46 mm Hg after one year. There were no serious complications. One patient experienced a brief episode of syncope. Another patient developed a pulmonary incompetence which was without hemodynamic significance. Percutaneous balloon pulmonary valvuloplasty offers an alternative method for treating pulmonary stenosis not only in children but also in adults.