Microsurgical transplantation of the osteo-cutaneous fibula as a free flap to reconstruct the defect following radical resection of a mouth floor's tumor is a well-known and often applied procedure. Anatomy of the vessels supplying this flap is recognized but it may have some rare and unexpected variations. In this case report we discuss the reconstruction of the middle and lateral parts of the mandible which was resected due to a T4 gingival tumor. Interestingly, the aforementioned segment of the fibula and the overlying skin island were supplied by different pedicles, both emerging from the posterior tibial vessels. Both flaps were transplanted using autologous arterial and venous grafts of the peroneal artery and vein in case of the fibula. We believe this case is worth publishing due to its relative rarity in the literature and the applied surgical method.