A higher than expected incidence of haemorrhagic stroke led researchers to suspend 3 major trials designed to compare the effects of hirudin with heparin. All 3 trials were investigating the effects of these antithrombotics in patients with myocardial infarction who were receiving thrombolytic therapy. This turn of events has raised serious questions regarding the optimal dose of both antithrombotics, with some researchers questioning whether heparin should be used at all in patients receiving streptokinase. Data from the halted trials, and details of new regimens for 2 of the studies, were presented at the joint 12th World Congress of Cardiology and 16th Congress of the European Society of Cardiology [Berlin, Germany; September 1994].