Between 1973 and 1987, 36 patients with 41 episodes of enterococcal endocarditis were seen at our institution. There were 22 episodes of native valve endocarditis (NVE) and 19 episodes of prosthetic valve endocarditis (PVE). The overall mortality before completion of therapy was 15% (18% due to NVE and 11% due to PVE). Among patients with NVE, involvement of the aortic valve was significantly associated with death or complicated illness (defined as the need for valve replacement before completion of antibiotic therapy or relapse of endocarditis after completion of therapy). Among patients who survived episodes of PVE, 69% were cured without surgical intervention. Gentamicin was administered in combination with a penicillin or vancomycin in the majority of episodes (mean duration of therapy with aminoglycosides: 5 weeks). Renal dysfunction occurred in 44% of patients who received gentamicin and occurred more frequently in patients with elevated serum creatinine levels before treatment. Our results suggest that enterococcal PVE can often be successfully treated with antibiotics alone, and they confirm the efficacy of gentamicin when it is administered in combination with cell wall-active agents for the treatment of endocarditis due to enterococci that lack high-level resistance to this agent.