None of the currently available antibiotic regimens is completely effective for the therapy of severe enterococcal infections. Recent studies have shown that a combination of penicillin plus gentamicin produces enhanced killing against virtually all strains of enterococci in vitro. We report four cases of enterococcal endocarditis and two cases of enterococcal meningitis that were successfully treated with penicillin and gentamicin, thus confirming the in vivo effectiveness of this combination of antibiotics against enterococci.