Recombinant tissue-type plasminogen activator (rt-PA) is currently the most commonly used drug for PTE thrombolysis. Like most thrombolytic medications, rt-PA carries a risk of significant bleeding, which is dose dependent. Thus, optimal dosing that can maximize benefits and minimize risks is of great importance. There is substantial controversy and debate regarding the optimal rt-PA dosage for thrombolytic therapy and whether the same dose should be used in all patients. Low dose of intravenous rt-PA for thrombolysis after acute myocardial infarction (AMI) had been suggested by previous studies. Experimental and clinical studies have indicated that a lower dose of rt-PA bolus may be potentially safer, and yet equally effective then the 2-h 100 mg rt-PA continuous infusion for PTE.