The Authors report their experience of the surgical treatment of cardiac prosthetic endocarditis. Between September 1974 and December 1988, 2,796 cardiac prostheses were implanted. An endocarditis in the follow-up of 23 patients involving 27 prostheses was diagnosed. The operative mortality was high in patients with mitral prosthetic endocarditis; in patients with infected aortic prosthesis operative mortality was low, but there was a high incidence of recurrence. The Authors emphasize the difficulty of diagnosis and the importance of the surgical treatment for eradication of the infection and for resolution of the haemodynamic defect.