Between 1972 and 1982, 27 patients underwent 29 prosthetic valve replacements for infective endocarditis. Fourteen cases (48%) were operated in the acute infectious phase. Most patients (71%) had signs of cardiac failure and surgery was often performed as an emergency (78%). Twelve aortic valve prostheses (10 mechanical + 2 bioprostheses) and 2 mitral bioprostheses were infected. Four patients (29%) died in the postoperative period; all were in functional Class IV and were reoperated as an emergency. The infection only persisted in 1 patient (7%). Three patients died during follow-up (3 year survival: 46%). Three replacement prostheses developed perivalvular leaks (21%) and 2 were reoperated. Fifteen cases (52%) were operated after the acute infection for secondary lesions. These lesions affected an aortic valve prosthesis in 14 cases (9 mechanical and 5 bioprostheses) and 1 mechanical mitral valve prosthesis. Operative mortality was nil. Three patients died during follow-up (3 year survival: 67%). Five replacement prostheses developed perivalvular leaks (33%) and 3 had to be reoperated. These results show: that the high operative mortality (29%) in the group operated during the acute infectious phase is related to the preoperative haemodynamic condition and not to persistence of the infection (only 1 case); secondly, recurrent perivalvular leaks were common in both groups due to the fragility of the tissues and were the main cause of late mortality.(ABSTRACT TRUNCATED AT 250 WORDS)