We assessed the appropriateness of surgical antibiotic prophylaxis in 6 teaching hospitals in Shiraz, Iran, using the American Society of Health-System Pharmacists guideline as a reference. We reviewed the medical records of 1,000 patients who underwent 1 of 9 different surgical procedures (1 procedure per patient). The proportion of procedures in which there was compliance with all guideline recommendations was 0.3%. The most common mistakes were overuse and misuse of antibiotics.