The early establishment of infarct artery reperfusion by intravenous thrombolytic therapy has improved survival after acute myocardial infarction. Investigations of reperfusion have focused on the effects of specific thrombolytic agents, anticoagulation, and platelet inhibition. However, little attention has been given to the relation of arterial blood pressure to thrombolysis, a factor that probably affects thrombolytic agent delivery to the obstructing thrombus.