Intraosseous infusion of fluid had been used in traumatology. Here we describe a clinical situation in which bone marrow is first used for drainage of venous blood in a free osteocutaneous flap. Two factors account for the survival of the large osteocutaneous flap in which venous anastomosis was impossible. (1) In the design of the arterial circuit and the major route of venous drainage, there were two ends of the peroneal artery of the osteocutaneous flap. Both its upper and lower ends were anastomosed to the anterior tibial artery of the recipient site to constitute an uninterrupted arterial circulation. This prevented stagnation of arterial flow and thrombosis of the arterial anastomosis. (2) The major route of venous drainage was through bone marrow. The initial congestion was finally overcome by the development of neovascularization. Bone scan showed good survival of bone with increased uptake of radioactivity. At 3 years follow-up, roentgenogram showed bone union, and the patient had no trouble walking. The continuity of the anterior tibial artery, which had been interrupted by trauma, was restored by this flap.