The study showed that there was an overall decrease in digital blood flow following radial artery harvesting. The resulting blood supply in the remaining ulnar artery still provided more flow to the thumb and index fingers than to the fourth and fifth fingers, indicating the existence of an autoregulatory mechanism operating to satisfy the physiologic needs of the fingers. The long-term results showed that the overall decrease in distal blood flow immediately after radial artery harvesting was significantly recovered by physiologic adaptation.