[en] After retransfusion of UV-irradiated own blood (UVB) as well as whole body UV-irradiation the flow properties of blood were improved. Patients with peripheral arterial occlusive disease showed a significant prolongation of maximal walking distance by 152% after UV treatment as well as an increased O₂ utilization. The levels of intraerythrocytic ATP and 2,3-PG were increased for patients as well as for healthy volunteers after UVB. This is discussed as a stimulation of glycolysis of red blood cells. It is assumed that the improvement of metabolism involves modified purines. (author)