The anterolateral thigh (ALT) flap is one of the most commonly used flap worldwide in reconstructive surgery, as both free flap and pedicled local flap. Here, we report the use of a free split anterolateral thigh (s-ALT) flap for reconstruction of a 14 cm × 16 cm soft tissue defect of the left upper posterior thigh region due to sarcoma resection in a patient. The ALT flap was harvested based on two musculocutaneous perforators from the right thigh and anastomosed to the contralateral descending branch of the lateral circumflex femoral artery (LCFA) in perforator-to-perforator manner, in order to gain more pedicle length and being able to cover the posterior thigh defect. The post-operative course was uneventful and the patient was discharged at 1 week post-operative. Eleven months after the operation, the aesthetic outcome was satisfactory with no functional deficit. Even though it requires technical skills and experience in perforator dissection, we believe that the s-ALT flap anstomosed to the contralateral LCFA in perforator to perforator fashion, may be a good solution in case of such a difficultly located extensive defect of the posterior thigh.