To study the influence of bacterial culture data on the clinical management of gangrenous or perforated appendicitis, we reviewed records of 104 patients who had been treated empirically with aminoglycoside antibiotics. Culture results appeared to influence antibiotic therapy in only 7 patients (7%). The routine cultures obtained at appendectomy affected therapy in only 2 patients. Discriminant analysis identified postoperative infectious complications and related factors as the principal determinants of culture utility. We conclude that, in patients with perforated appendicitis treated empirically with aminoglycoside combination regimens, culture results were seldom used for clinical management except in instances of postoperative infectious complication. Routine cultures and Gram's stains of perforated appendicitis, however, should still be obtained (1) to allow epidemiologic tracking in the hospital; (2) to identify organisms that are recovered infrequently but may cause serious disease (eg, Clostridium); and (3) because newer antibiotics are replacing aminoglycosides in the treatment of perforated appendicitis.