Recombinant tissue plasminogen activator (rt-PA) is currently the most commonly used thrombolytic drug in patients with pulmonary thromboembolism (PTE). Optimal dosing with maximal benefits and minimal risks is of great importance. Considering the lower body weight in general Chinese population, we compared the efficacy and safety of lower dose rt-PA 50mg/2h regimen with the FDA-approved rt-PA 100mg/2h regimen in selected PTE patients.