 Perioperative hypothermia brings numerous and recognized postoperative complications. Active warming intraoperatively helps to maintain body temperature in the postoperative period, but there are few studies in Brazil, assessing the effect of prewarming in maintaining normothermia. It is believed that prewarming with forced air warming system keep the body temperature during intra and post-operative. This study aims to evaluate the effect on prewarming maintaining body temperature of patients undergoing elective surgery of Gynecology specialty using the forced air warming system. The study is experimental design, controlled type randomized clinical trial, with simple blinding for patients. Eighty adult patients undergoing gynecological surgery in the art, with a surgical time of at least an hour will be randomized and allocated into experimental groups - prewarming system with forced air warming system for 20 minutes, and control - Prewarming with sheet and blanket for 20 minutes. The patients will be kept warm during the anesthetic-surgical procedure. The measurement of temperature will be using a tympanic thermometer. Participants will be followed from receiving the surgical center to the end of surgery. Data will be recorded in validated instrument. Data analysis will be used the Model Linear Mixed Effects and the Structure Error Auto-Regressive. 