Streptococcus equisimilis (Lancefield group C), an unusual cause of nosocomial surgical infection, was isolated from two orthopedic postoperative wound infections. Both operations had been performed by the same surgeon within a three-day period. Examination of the surgeon revealed perianal dermatitis from which S. equisimilis was isolated. The organism was also recovered from the surgeon's nose and rectum. The wound infections responded to treatment with penicillin derivatives. The surgeon was successfully treated with topical bacitracin and oral penicillin and vancomycin. This report documents the pathogenicity of the C Streptococcus in postoperative infection and suggests a possible nosocomial source of the organism.