Antibiotic prophylaxis after basilar skull fractures remains controversial. Previous studies have not clearly delineated the utility of prophylactic antibiotics in this setting. We undertook this study to determine if antibiotic prophylaxis after basilar skull fractures prevented meningitis. We performed a formal systematic review of previously published studies after a computerized search with use of the MEDLINE data base (1970-1996). Fourteen studies were identified, and 12 studies met the criteria for inclusion. Study design and quality were assessed by two independent investigators with use of a predetermined protocol. A total of 1,241 patients with basilar skull fractures were included; 719 patients received antibiotics, and 522 patients did not receive antibiotics. Overall results suggest that antibiotic prophylaxis did not prevent meningitis among patients with basilar skull fractures (odds ratio [OR] = 1.15; 95% confidence interval [CI] = 0.68-1.94; P = .678). Patients with basilar skull fractures and cerebrospinal fluid leakage were analyzed separately (OR = 1.34; 95% CI = 0.75-2.41; P = .358), as were children (OR = 1.04; 95% CI = 0.07-14.90; P = 1.000). Antibiotic prophylaxis after basilar skull fractures does not appear to decrease the risk of meningitis.