Infective endocarditis is associated with a high mortality, but previous studies have suggested that the major complications of the condition might be prevented by early surgery. Of 50 patients treated for infective endocarditis at the Montreal Heart Institute from 1977 to 1982, 30 were treated nonsurgically and the remaining 20 underwent early valve replacement before preoperative antibiotic therapy was completed. Of these 20, 14 had native valve endocarditis and 6 prosthetic valve endocarditis. The organisms involved were Streptococcus sp in 11, Staphylococcus aureus in 2, gram-negative organisms in 3 and Candida parapsilosis in 1. Blood cultures remained negative in three patients. There were three early deaths (15%) following operation and one late death (5%). Infection on implanted prostheses did not recur, but reoperation was required in one patient because of prosthetic dehiscence 7 months after initial implantation. All resected valves displayed evidence of infection. Follow-up was obtained in all survivors. After an average follow-up of 26 months, 12 patients remained in functional class I and 4 in class II (New York Heart Association classification). Early valve replacement has resulted in improved survival of patients with infective endocarditis and is now associated with a low operative mortality and morbidity.