The use of vancomycin is increasing for the treatment of serious life-threatening staphylococcal and other bacterial infections, including infective endocarditis, in patients who are allergic to the penicillins. The literature through 1978 reveals approximately 55 cases of infective endocarditis treated with vancomycin alone or with combined antibiotic therapy. Many of these 55 patients were treated by different clinicians, were given variable regimens of therapy, received other therapy before vancomycin, had associated valve replacement; various amounts of data were provided for the reported cases. A summary of these reports indicates a cure in 48 (87%) of the 55 patients. Recent in vitro and in vivo animal and patient data indicate that vancomycin alone or as part of combined therapy is bactericidal and curative in patients allergic to penicillin for infective endocarditis caused by staphylococci and streptococci-both enterococcal and nonenterococcal (Streptococcus bovis and viridans group streptococci) infections. In this study, 10 patients with infective endocarditis were treated with vancomycin or combined therapy; seven were cured. Five of the 10 patients with infective endocarditis caused by viridans streptococci were cured with combined vancomycin-streptomycin given in short-term therapy for two weeks.