Twenty-five patients underwent early and elective valve replacement for infective endocarditis during a 5-year period between April 1985 and March 1991. Indications for urgent surgical intervention performed at a mean 32 (range 6-47) days after admission were intractable heart failure, systemic emboli, septic multiorgan failure and the presence of vegetations. Indication for elective surgery was persistent (mean 42 (range 17-56) days) infection after appropriate antibiotic therapy. Twenty patients (80%) had a native valve endocarditis; five (20%) had prosthetic valve involvement. A total of 30 valvular prostheses were implanted: 22 (73.3%) were aortic (21 mechanical and one biological); eight (26.7%) were mitral (all mechanical). All unstable patients referred were treated before surgery in the intensive care unit and subjected to blood ultrafiltration to restore satisfactory circulatory parameters. No patient underwent cardiac catheterization; all patients were operated upon on the basis of echocardiographic data alone. One patient (4%) died during hospitalization; two (8%) died later at 48 and 12 months after the first intervention. The reoperation rate was 12%. After a mean follow-up of 49 (range 1-71) months, 21 of the survivors (95%) were in New York Heart Association functional class I or II; the actuarial 5-year survival rate was 87%. Precise preoperative assessment of early operative indications and timely association of medical therapy in unstable patients could represent a step forward in the treatment of acute infective endocarditis.