Acute and subacute arterial occlusions of between 4.5 and 29 cm long could be dissolved in 11 patients by infiltration of small amounts (4000 to 110 000 U) of streptokinase or urokinase directly into the thrombus using a catheter. Use of a Grüntzig catheter enabled dilatation of possible stenoses during the same session. In 3 femoro-popliteal obliterations where lysis and catheter dilatation did not lead to sufficiently patent lumina occlusion recurred. In 3 patients with wide-ranging obliteration of the femoral, popliteal and almost all the arteries of the calf almost complete revascularisation could be achieved. Only transient slight side effects of lysis and coagulation disturbances were observed systemically. For prophylaxis of reobliteration platelet aggregation inhibitors are given for pre- and long-term aftercare.