Seventy-two consecutive patients with severe aortic stenosis and impaired by left ventricular ejection fractions (EF less than 40%) underwent percutaneous aortic valvuloplasty between September 1985 and November 1987. Forty-five patients had been turned down by the surgeons because of their age (29 patients over 80 years of age), their impaired left ventricular function or associated pathologies. Valvular dilatation with 15 to 23 mm diameter balloons resulted in a reduction of the transvalvular pressure gradient from 63 +/- 21 to 26 +/- 11 mmHg (p less than 0.001) and an increase in valve surface area from 0.48 +/- 0.15 to 0.91 +/- 0.32 cm2 (p less than 0.001) but with large individual variations. No cases of aggravation of associated aortic insufficiency were observed after the procedure. One 98-year old woman died during the dilatation and 4 other patients died during the hospital period. Immediate clinical improvement was observed in 80 per cent of patients. During the one-year follow-up period, 33 patients died, 31 of cardiac causes. Of the 34 survivors at one year, 21 had maintained their clinical improvement. A repeat hemodynamic study was performed in 22 patients 7 months after valvuloplasty. Eleven patients had restenosed and their hemodynamic parameters had practically returned to pre-valvuloplasty values. The left ventricular ejection fractions of the 11 patients without restenosis had increased from 28 +/- 7 to 40 +/- 18 per cent (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)