The lungs are the only organ receiving the entire cardiac output. Therefore, they are the point of convergence for the entire molecules of the thrombolytic agent, independent from the route of administration. So that lower doses of the TT might be effective in PE, with the additional benefits of enhancing its safety profile. The percutaneous endovenous intervention for deep venous thrombosis has suggested an exquisitely favorable pulmonary response to low-dose thrombolysis. The aim of the present study was to assess the effects of low-dose (25mg) prolonged administration (in 6 hours) of tissue type plasminogen activator (tPA) on in-hospital mortality and outcomes in patients with massive PE.