Background. Controversy exists regarding the timing of thrombolytic administration and rupture rate. Methods. Hospital records at St. Luke's-Roosevelt Hospital of the 4 study patients were reviewed and compared with those of 41 patients from a group of 537 patients concurrently admitted with a diagnosis of myocardial infarction (MI). Results. Four patients experienced ventricular free wall rupture after having a MI between November 17, 1993, and July 28, 1995. All received tissue plasminogen activator. In 1 patient, pericardial effusion associated with a pseudoaneurysm was discovered in the operating room. The 3 others developed clinical pericardial tamponade before surgery. All 4 patients survived and left the hospital on postoperative days 10, 11, 11, and 82, respectively. During this same time period, 537 patients were admitted with MI, 41 of whom died; the study's 4 patients were compared with these 41. Conclusions. These data demonstrate that rupture of the ventricular free wall can occur early after thrombolytic therapy and may have a subacute course. Prompt diagnosis and surgery offer excellent chances of surviving this fatal condition. (C) 2000 by The Society of Thoracic Surgeons.