&NA;Four controlled trials and one case control study have presented data supporting the efficacy of perioperative administration of antibiotics in reducing the rate of infection following clean neurosurgical procedures. Their results are, for the most part, consistent with uncontrolled studies reported since 1980. Taken together, these studies clearly and consistently demonstrate the value of perioperative antibiotic prophylaxis in clean neurosurgical operations. (Neurosurgery24:401‐405, 1989)