BACKGROUND: The occurrences of pressure sores have an extensive impact on patients and the medical team. Pressure sores decrease quality of life and productivity, as well as increase the overall cost of treatment. The purpose of this study was to identify the risk factors associated with pressure ulcers among surgical patients. METHODS: Data were collected from 588 patients who underwent general anesthesia. The data included age, gender, weight, height, body mass index, ASA status, surgical position, anesthesia time, pre-and postoperative hemoglobin concentration, serum albumin, NYHA class, co-morbidity, steroid use, body temperature, use of warming water mattress and preoperative hospital admission day. The patient's skin was inspected closely before surgery and again within 24 hours after surgery and the locations and severity of skin breakdowns were assessed. RESULTS: Twenty-five patients (4.3%) developed pressure sores during surgery. The hemoglobin concentration change between the preoperative and postoperative period (> or =2 g/dl), position during surgery, length of stay before operation (> or =4 days), anesthesia time (> or =5 hours) and decrease in body temperature (> or =0.5degrees C) were significantly related to the development of pressure sores (P < 0.05). CONCLUSIONS: Five risk factors for pressure ulcers were confirmed. The anesthesiologist can decrease hemoglobin and modify body temperature; therefore, attention should be given to these risk factors during the operation.