Reteplase (BM 06.022; r-PA) is a recombinant peptide which consists of the kringle 2 and protease domains of human tissue-type plasminogen activator. It has been developed as a thrombolytic treatment for acute myocardial infarction (AMI). The half-life of reteplase allows administration as a double-bolus injection (second injection given 30 minutes after the first) rather than by the prolonged and, in some cases, more complex intravenous infusion regimens that are required for most other thrombolytic agents. Reteplase produced rapid and effective coronary artery thrombolysis in a number of dose-finding and comparative studies. Double-bolus administration of reteplase 10U + 10U produced significantly higher coronary artery patency rates than accelerated alteplase (100mg as a 1.5-hour infusion) in patients with AMI in the RAPID-II study. The 10U + 10U reteplase regimen produced a 35-day survival rate at least equivalent to that seen with a 1-hour infusion of streptokinase 1.5 million units in 5986 patients in the INJECT study, which was designed to demonstrate equivalence between treatments. As with other thrombolytics, bleeding was the most common adverse event seen in reteplase recipients. No significant differences in the overall risk of haemorrhage were observed between reteplase and either accelerated alteplase or standard streptokinase treatment in clinical trials. The risk of stroke in reteplase recipients appears to be similar to that for other thrombolytic agents [1.2% incidence in 3288 patients treated with reteplase 10U + 10U in clinical trials (0.76% for haemorrhagic stroke)], although accurate statistical assessment of the relative risk is not possible for the data available to date. Thus, reteplase is an effective thrombolytic agent which can be administered as a double-bolus injection regimen rather than as a prolonged infusion. Together with acquisition cost and general pharmacoeconomic data (which are not yet available), the results of GUSTO-III (a trial comparing double-bolus reteplase with accelerated alteplase in 15 000 patients) will have a major influence on the pattern of use of reteplase. In the meantime, data from the available clinical trials suggest that reteplase is a fast-acting and effective thrombolytic treatment for patients with AMI.