One-hundred-and-thirteen patients with endocarditis and valvular insufficiency were studied retrospectively with special regard to indications for operation and the optimum time for cardiac valve surgery. Thirty patients (group I) had acute, 63 (group II) subacute and 20 (group III) prosthetic valve endocarditis. Group I: Eleven patients underwent surgery in the acute stage, 8 while bacteremic; 5 of the latter died perioperatively. Of the 19 patients treated medically, 16 died. Group II: All patients underwent operation in a bacteria-free state. The mortality was 5%. Group III: Eight patients had early (less than 60 days postoperatively) and 12 late endocarditis. Total mortality was 40% (71% early and 25% late mortality). Ten patients underwent reoperation, with a mortality of 20%, compared with 60% in the medically treated group. The results support the indication for early operation in acute endocarditis with progressive cardiac failure and renal failure and prosthetic valve endocarditis, even during bacteremia.