Sixty-two patients with ninety injuries to the radial or the ulnar artery, or to both of these arteries, had arterial repairs using microvascular techniques in three medical centers. Twenty-six of the twenty-eight patients who had an ischemic hand secondary to injuries to both arteries and a successful operative repair had at least one patent vessel at follow-up. Of the other two patients, one had an amputation through the forearm for ischemia of the hand and the other had a viable hand supplied by collateral vessels, although both the radial and the ulnar arteries were thrombosed. The over-all success rate for all repairs was 54%. After 47% of the one-artery and 57% of the two-artery lacerations, the vessels were patient at follow-up. Repairs of acute sharp transections of the radial artery within thirty-six hours of injury were most successful. Of the factors other than operative technique that strongly influence vessel patency after repair, back pressure in the distal arterial stump and the extent of the ischemia of the hand relative to its normal blood supply ( a function of the completeness of the palmar arch) appear to be the most important.