T Objective: Intraoperative hypothermia causes increased bleeding, increased transfusion risks, long of intensive care unit stay and subsequently higher medical costs. This study aimed to determine the effects of hypothermia on perioperative bleeding and intensive care unit stay duration in patients undergoing major oncological urology surgery. Materials and Methods: Following approval of this study by the ethics committee, demographic characteristics, surgery type, operation time, lowest perioperative body temperature, hemodynamic parameters, the use of heating blanket during surgery, the amount of bleeding and transfusion, postoperative long of intensive care unit stay in patients who underwent open major urological surgery during 2015-2018 were retrospectively evaluated. Esophageal probe was used for temperature monitoring following anesthesia induction and a body temperature of <36 °C was considered to indicate hypothermia. Results: A total of 68 patients without a heating blanket (n=57) and using a heating blanket (n=11) were included in the study. The intraoperative lowest recorded body temperature was 32.1 °C, and hypothermia (<36 °C) developed in 63.6% of patients for whom heating blankets were used and in 94% of patients for whom heating blankets were not used. The amount of intraoperative bleeding was significantly low in patients for whom heating blanket was used (p=0.03). Conclusion: Perioperative hypothermia is a very frequent and preventable clinical condition that increases long of intensive care unit stay, mortality, and morbidity in geriatric patients and in patients undergoing major surgery. Based on our results, less bleeding and decreased need for intensive care unit stay were noted owing to the prevention of intraoperative hypothermia