BACKGROUND: Early cytomegalovirus (CMV) reactivation infections have been found to be associated with a number of stress responses such as severe bacterial infection. Intraoperative hypothermia is known to be a significant physiological stressor. Hence, we sought to evaluate a relationship between intraoperative hypothermia during liver transplantation and early CMV infection. METHODS: Relationships between intraoperative hypothermia and early CMV infection were assessed using univariate and multivariate analysis. RESULTS: There were 11 of 100 patients who had CMV infection detected within the first 30 days after the transplant and 16 of 100 in the next 3 months after the transplant. The median intraoperative temperature (34.4 degrees C) of those who subsequently developed early CMV infection was significantly lower than that in patients who did not develop early CMV infection (35.3 degrees C; P = 0.032). Multivariate analysis showed that only hypothermia was an independent predictor of early CMV infection (odds ratio 2.8, 95% confidence intervals 1.2-6.4; P = 0.047). CONCLUSIONS: Intraoperative hypothermia during liver transplantation increases the risk of CMV infection in the 1st month postoperatively and active warming seems to reduce this risk.