Perioperative bleeding is a critical challenge in adolescent idiopathic scoliosis (AIS) surgery. Preventing hypothermia is associated with decreased development of coagulopathy, blood transfusion rate in various surgery groups. We hypothesized that blood loss would be reduced in patients who were kept normothermic by implementation of aggressive warming methods in AIS. This randomized-controlled study included patients aged 12-18 years who were scheduled to undergo elective scoliosis deformity correction surgery. The patients were divided into two groups: the study group (Group S) was heated aggressively with three different heaters including compressed-air blower heater, intravenous fluid heating, and a heating bed, while the control group (Group C) received only heating with a standard compressed-air blower heater. Tympanic, esophageal, and axillary body temperatures were measured, and hemoglobin and arterial blood gas analyses were repeated during the anesthesia period. Daily bleeding-coagulation parameters were recorded on postoperative days 0, 1, and 2. Forty-eight patients were randomized, and 39 patients were included into the final analysis. The total amount of intraoperative bleeding (