Patients with a recent (less than 10 days) proximal deep vein thrombosis of the 
leg or pelvis are candidates for thrombolysis as the major benefit over heparin 
seems to be the prevention of the postphlebitic limb, an aim which is still not 
proven in a satisfactory manner. Nonocclusive thrombi appear to lyse more 
readily than occlusive thrombi. For this indication the optimal dose regimens 
for the three thrombolytic drugs (streptokinase, urokinase, alteplase) are not 
established. Acute massive pulmonary embolism with hypotension or shock should 
be treated with thrombolytic drugs and, pending the outcome in the first hour, 
be considered for pulmonary embolectomy. Major acute pulmonary embolism with 
haemodynamic instability responds well to thrombolysis. Whether thrombolysis is 
superior to heparin in subacute intermediate pulmonary embolism has not been 
proven unequivocally in terms of mortality or clinically important endpoints. 
Systemic administration of thrombolytic drugs for peripheral arterial occlusion 
has been abandoned for catheter-directed and intraoperative intra-arterial 
repeated bolus or short-term infusions. The efficacy and safety of intravenous 
thrombolytic treatment following a major ischaemic stroke is presently being 
tested in large scale trials; its use must be restricted to experimental 
protocols.