목적: The anterolateral thigh (ALT) free flap is widely used for various reconstructions in the head and neck. However, its use in the patient with high body mass index (BMI) is difficult for the low pliability and preoperative prediction is important for the selection of harvest site. 방법:We retrospectively reviewed 98 patients with reconstruction using an ALT free flap between May 2013 and Feb 2015. We recorded history, BMI, stage of tumor, course of operation, postoperative period, oncological treatment, clinical outcome, and follow-up. We checked the ALT thickness in preoperative PET-CT and its effects on the surgical outcomes. 결과:The mean age was 62 years. The operations included resection of the tumour, neck dissection, and reconstruction of the defect with an ALT free flap. All donor sites were closed primarily. Two patients (10%) developed flap failure that required reoperation. There were no other complications or late problems of the donor site. Positive correlation was seen between preoperative ALT free flap thickness and operation time parameters by univariate linear regression analysis. 결론:ALT thickness in preoperative PET-CT is a possible predictor of surgical convenience and outcomes and can affect the selection of the flap candidates.