Surgical site infection (SSI) is a common and preventable complication of surgery, but the relative importance of individual measures recommended by guidelines has not been determined. Elective general surgical, neurological, and orthopedic procedures requiring antibiotic prophylaxis from a 3-month period were retrospectively studied to determine concordance with SSI prevention guidelines and to identify factors which predicted the development of SSIs. A total of 216 surgeries were reviewed, with 18 SSIs (8.3%). A mean of 1.4 antibiotic prophylaxis errors per surgery were identified, with correct antibiotic type identified for 64%, antibiotic timing for 83%, supplemental antibiotic dosing for 34%, and antibiotic duration of less than 24 h for 44%. Normothermia was present in 79% of surgeries, and normoglycemia was present in 17%. Univariate analysis of the SSI rate identified four significant factors. National and international surveillance programs (9, 33) and numerous guidelines (1-3, 11, 19, 24, 26) have been developed to prevent surgical site infection (SSI), the most common nosocomial infection in postsurgery patients. These guidelines emphasize the role of appropriate evidence-based antibiotic prophylaxis, hair removal by clipping as needed (31), avoidance of hypothermia (except in cardiac surgery) (16), and normoglycemia for diabetic patients (17) to reduce SSI rates.A recent pilot project at our institution prior to the current study demonstrated that implementation of such guidelines can be successful locally, but compliance elsewhere has been shown to be poor (4, 18). Furthermore, there is a high prevalence of multidrug-resistant bacteria in Singapore hospitals, and inappropriate antibiotic use, including for SSI prophylaxis, can aggravate the selective pressure for antimicrobial resistance (15).We evaluated SSI prevention practiced in our hospital to assess concordance with published international evidencebased SSI prevention guidelines and the effects of failure to comply with subsequent SSI rates.