Between January 1980 and May 1990 17 patients underwent surgery for prosthetic valve endocarditis at Cardiosurgical Department of Bologna University. Ten patients were female and seven male, the average age was 33 years (range 19 to 67 years). The interval from valve replacement to onset of symptoms of prosthetic valve endocarditis was less than 2 months in 5 patients and longer than 2 months in 12 patients. Sixteen of 17 infected prostheses were mechanical and one biological. All patients were surgically treated and the infected prostheses replaced with new valve prostheses. The hospital mortality rate for early prosthetic valve endocarditis was 60%, for late endocarditis was 16.5%, global hospital mortality was 29.4%.