PURPOSE: Despite advances in infection control practices, Surgical Site Infections (SSIs) remain a substantial cause of morbidity and mortality among hospitalized patients. This study was undertaken to determine prospectively the incidence of postoperative wound infections in surgical patients and to identify the risk factors associated with the development of wound infections. METHODS: Prospective data on 761 surgical operation patients in the department of surgery at Ewha Womans University Mokdong Hospital were collected over a 7 month-period from May 1, to December 31, 2001. The Centers for Disease Control and Prevention (CDC)'s definitions of surgical wound infections were used. RESULTS: A total of 761 patients were observed over 30 days. The overall incidence of wound infection was 2%. SSIs were significantly associated with the degree of wound contamination (P=0.0004). The infection rate increased as the degree of wound contamination increased from clean (1.4%) through clean-contaminated (1.8%) and contaminated (1.8%), to dirty- infected wound (12.7%). The infection rate was related with the American Society of Anesthesiologists (ASA) preoperative assessment score (P=0.00153). There were no SSIs from laparoscopic surgery. The duration of operation was not associated with an increase in wound infections. Enterococcus faecium and Staphylococcus aureus were the most frequently isolated organisms. Three out of the five (60%) cases of E. faecium were vancomycin-resistant enterococci (VRE) and all of three cases of S. aureus were methicillin- resistant Staphylococcus aureus (MRSA). CONCLUSION: This study confirms that the degree of wound contamination is a significant preoperative risk factor for SSI. Many antibiotic-resistant bacteria such as MRSA and VRE were isolated. Accordingly, infection control practitioners need to consider this risk factor in the design of effective infection control strategies. There should be another safe and feasible option available for the treatment of selective patients.