The distal arterial bypass for an ischemic lower extremity with inadequate distal target vessels can be a technical challenge. High outflow resistance combined with the difficulty of the small vessel anastomosis may lead to bypass graft failure. We have used a radial artery flow-through (RAFT) flap to facilitate these difficult bypasses in 10 patients from Nov 1999 to Jan 2002. All patients had limb threatening ischemia. All but one had non-healing ulcers. Seven had diabetes mellitus. Five had previously undergone a conventional bypass. The bypass patency rate was 80% with an overall limb salvage rate of 80%. There were no cardiac events or hand ischemia following the RAFT flap harvest in this small series. We hypothesize that the increased bypass patency was primarily due to the built-in modulating artiovenous fistula of the flow-through flap which maintains a high flow though the bypass graft in the face of high distal outflow resistance. This hypothesis was tested in the rat epigastric flow-through flap model which demonstrated a four-fold increase of epigastric blood flow over a 3 hour period upon tying off the outflow branches. The flow-through flap bypass was patent 70% of the time as compared with 0% for the control arterial interpositional graft in this model. We believe the RAFT flap bypass presents a new option in limb salvage operations for peripheral arterial occlusive disease especially when there are concomitant non-healing ulcers. We present our experience and complications encountered with this technique.