Between January 1972 and March 1983, 123 patients with isolated non dystrophic aortic insufficiency underwent aortic valve replacement. During a mean follow-up period of 4.3 years per patient, 25.6 p. 100 of the patients died, including a 4.1 p. 100 hospital death rate. The actuarial survival rate was 74 p. 100 at 5 years and 62 p. 100 at 10 years. The main causes of mortality were heart failure, dysrhythmias and sudden death. A study of prognostic factors based on the preoperative data showed that clinical, radiological, electrocardiographic and haemodynamic signs were informative. In agreement with other authors, we found that preoperative cardiac dilatation and left ventricular dysfunction were predictive of a poor prognosis.