Background: The contribution of antibiotic prophylaxis to reduce surgical wound infection for some procedures is well known. In spite of extensive knowledge about the effectiveness of antibiotic prophylaxis, its administrative regimens are often inappropriate. Methods: Antibiotic prophylaxis was evaluated in a university-affiliated community teaching hospital. Data were collected from medical records of patients undergoing cholecystectomy, hysterectomy, and herniorrhaphy during a 9-month observation period. A total of 598 procedures were observed. Data were collected about the patient, the surgery, and the antibiotic prophylaxis. Results: Based on the existing guidelines, the choice to use the prophylactic antibiotic was correct in 75% of the cases. Of these cases, only 3% of the patients received the recommended regimen according to the proposed procedure. It was verified that antibiotic prophylaxis was performed more frequently in patients undergoing open cholecystectomy than laparoscopic cholecystectomy (P = .004). In 46% of the cholecystectomies, more than 4 doses were administered. In hysterectomy, a single dose was used in 54% of the patients, and the antibiotic was administered preoperatively in 80% of the cases. Prophylactic antibiotics were used in 47% of herniorrhaphies. Conclusion: The surgeons infrequently met the hospital guideline for antibiotic prophylaxis, and compliance varied by type of procedure. (AJIC Am J Infect Control 1999;27:296-300)