In 23 patients suffering from intermittent claudication due to chronic occlusions of the femoral artery proved on angiography, a double-blind study was performed to compare the effects of treatment with oxyfedrine and interval-training and of interval-training alone. The claudication distance, physical work capacity and physical work intensity were measured on the treadmill before, during and after 10-weeks training period in each case. After training, the walking ability improved in both groups, however, quantitatively being more pronounced in the oxyfedrine group. In the placebo group, the increase in physical work intensity was mainly caused by the improvement of walking ability in patients with higher levels of performance at the beginning of the training. In the oxyfedrine group, on the other hand, a continuous and regular increase in physical work intensity was found at all levels of performance and during the whole training period. For the differences found, blood supply lowering mechanisms after physical training and improvement of collaterals after combination oxyfedrine and physical training are discussed. The possibility of additive action of the pharmacologic treatment and physical training are pointed out.