BACKGROUND: The Allen test is used worldwide for radial artery graft removal. The postoperative examination of our patients' hand function and circulation proved that beside the transient neurological complications chronic hand circulatory disorders may arise. AIM: To develop a non-invasive method suitable for an objective evaluation of the hand's circulation to make it possible to use radial arteries safely for the revascularization of coronary arteries. METHODS: We examined 35 patients. After selective compression of the radial and ulnar arteries of both hands, we injected 400 MBq (99m)Tc-HSA intravenously and acquired 240 images, each of 1 s. After 30 s we released the ulnar artery first, and after 120 s the radial artery, too. Then computer analysis was performed. RESULTS: The patients could be divided into two groups. In the majority of them, releasing only the ulnar artery resulted in a good circulation of the fingers. It meant that the time-activity curve rapidly reached its maximum, and the activity did not change even after releasing the radial artery. In a smaller proportion of the patients the activity of the fingers increased only slowly, and did not reach a plateau even after 30 s. Following the release of the radial artery a further increase in the activity could be observed. We assume that the latter patient group is at risk of consequent circulatory disorder of the fingers after the removal of the radial artery, whereas in the former group the artery could be removed safely. CONCLUSIONS: Hand perfusion with (99m)Tc-HSA is useful in patients selected for coronary bypass operations, so we recommend the introduction of this method as a routine examination before the removal of the radial artery in patients with an abnormal Allen test.