The authors report a case of a free fibular graft that was successful as a result of venous return delivered through the bone marrow. A 26-year-old man underwent reconstruction of the left tibia and a soft-tissue defect of the lower leg. A free vascularized fibular bone and skin flap was elevated. The fibular vessels were anastomosed to the dorsalis pedis vessels. The elevated fibular bone was fixed to the tibia. The next day, reanastomosis was necessary because of venous thrombosis. However, the fibular vein rethrombosed, but blood flow was ascertained by Doppler flowmetry, with darker blood flow being recognized from the edge of the flap. Four days after surgery, the skin color gradually improved, and the flap had almost completely taken. On retrospective evaluation, the authors concluded that this flap succeeded because venous return was routed through the bone marrow in the free fibular graft.