BACKGROUND/OBJECTIVE: Inadvertent intraoperative hypothermia (core temperature <360 C) is a recognized risk in surgery and has adverse consequences. However, no data about this complication in China are available. Our study aimed to determine the incidence of inadvertent intraoperative hypothermia and its associated risk factors in a sample of Chinese patients. METHODS: We conducted a regional cross-sectional survey in Beijing from August through December, 2013. Eight hundred thirty patients who underwent various operations under general anesthesia were randomly selected from 24 hospitals through a multistage probability sampling. Multivariate logistic regression analyses were applied to explore the risk factors of developing hypothermia. RESULTS: The overall incidence of intraoperative hypothermia was high, 39.9%. All patients were warmed passively with surgical sheets or cotton blankets, whereas only 10.7% of patients received active warming with space heaters or electric blankets. Pre-warmed intravenous fluid were administered to 16.9% of patients, and 34.6% of patients had irrigation of wounds with pre-warmed fluid. Active warming (OR = 0.46, 95% CI 0.26-0.81), overweight or obesity (OR = 0.39, 95% CI 0.28-0.56), high baseline core temperature before anesthesia (OR = 0.08, 95% CI 0.04-0.13), and high ambient temperature (OR = 0.89, 95% CI 0.79-0.98) were significant protective factors for hypothermia. In contrast, major-plus operations (OR = 2.00, 95% CI 1.32-3.04), duration of anesthesia (1-2 h) (OR = 3.23, 95% CI 2.19-4.78) and >2 h (OR = 3.44, 95% CI 1.90-6.22,), and intravenous un-warmed fluid (OR = 2.45, 95% CI 1.45-4.12) significantly increased the risk of hypothermia. CONCLUSIONS: The incidence of inadvertent intraoperative hypothermia in Beijing is high, and the rate of active warming of patients during operation is low. Concern for the development of intraoperative hypothermia should be especially high in patients undergoing major operations, requiring long periods of anesthesia, and receiving un-warmed intravenous fluids.