• It is thought that the clot-specific activity of tissue plasminogen activator, used in the treatment of acute myocardial infarction, makes bleeding complications less common than does the use of either streptokinase or urokinase. The incidence of intracerebral hemorrhage complicating the use of tissue plasminogen activator has been estimated to be 0.68%. This is a report of the rupture of an intracranial arteriovenous malformation complicating the use of tissue plasminogen activator therapy. Theories for the mechanism of hemorrhage in this instance are presented, as are suggestions for future use of the enzyme.