Patients undergoing surgery in the park-bench position are at high risk of developing intraoperatively acquired pressure ulcers (IAPUs). The purpose was to examine retrospectively risk factors associated with IAPUs in the park-bench position. This study was conducted at a general hospital during the period of September 2010 to September 2012. Twenty-one potential risk factors were evaluated using data obtained from the hospital database. IAPUs developed in 30 of 277 patients (11%). Perspiration was statistically found to be independently associated with IAPUs [OR 3·09, 95% confidence interval (Cl) 1.07–8·58, P = 0·037]. A length of surgery of more than 6 hours was identified to be likely associated with IAPUs (OR 2·64, 95% Cl 0·84–9·08, P = 0·095) compared with less than 6 hours. Furthermore, there was an interaction between the length of surgery and the core temperature; that is, when the length of surgery was more than 6 hours, a core temperature of more than 38·1°C at the end of surgery had a higher odds ratio (8·45, 95% Cl 3·04–27·46, P < 0·001) than that at a lower core temperature (3·20, 95% Cl 1·23–8·78, P = 0·017). These results suggest that perspiration and core temperature are preventable causative factors of pressure ulcers, even under conditions of prolonged surgery in the park-bench position.