It is difficult to determine the surgical indications of asymptomatic chronic aortic regurgitation (AR). This study was undertaken in 205 patients with pure AR, operated between 1970 and 1982: 136 patients were symptomatic (Classes III and IV of the NYHA, +/- cardiac failure +/- angina, mean age: 49.5 years). Sixty nine asymptomatic patients (Classes I and II of the NYHA without cardiac failure or angina, mean age: 42 years). The prognostic value of 58 variables was studied in these two groups. The mortality during the first postoperative month was 14% in the symptomatic patients and the 5 year survival rate was 68.7%; this was significantly lower in patients with ECG changes of systolic left greater than or equal to ventricular overload, with radiological cardiomegaly (cardiotolerance index 0.60) with calcific aortic valve disease, with raised arterio-venous difference and/or low cardiac output, and with a low ejection fraction. In the asymptomatic group, the hospital mortality was zero and the 5 year survival rate 86.8%. This was significantly decreased in patients with an increased PR interval and a low cardiac index. It is possible that the small number of patients did not demonstrate the predictive value of left ventricular function in asymptomatic patients (a hypothesis suggested by the causes of secondary mortality which were the same in both groups of patients).(ABSTRACT TRUNCATED AT 250 WORDS)