19 patients were treated with streptokinase and (or) urokinase for primary thrombosis of the subclavian and (or) axillary vein (Paget-von-Schroetter-syndrome) of 2 to 28 days' duration. Phlebograms revealed significant improvement in 18 of the 19 patients (complete recanalization in 11, partial recanalization in 7). In those 17 patients whose symptoms had been present for up to 2 weeks the clinical outcome was entirely independent of the delay between the appearance of first symptoms and the start of fibrinolytic therapy, and even in the 2 patients wih an even longer delay complete recanalization was achieved in one (delay of 3 weeks) and partial recanalization in the other (delay of 4 weeks). However, since major clinical improvement occurs also spontaneously in most patients, a clear indication for fibrinolytic therapy exists only in particularly young patients and in those patients who depend on an absolutely perfect function of their upper extremities. In addition, the good results obtained with delayed fibrinolytic therapy justify extending this indication to those remaining patients in whom prior conservative management with elevation of the arm and anticoagulant therapy does not result in sufficient clinical improvement.