We report three cases of inadvertent thrombolytic administration to patients with cardiovascular diagnoses masquerading as acute coronary thrombosis presenting to tertiary care private hospital. Despite a final diagnosis of myocarditis, aortic dissection, and pericarditis, the initial presentation and electrocardiogram were believed to indicate an acute myocardial infarction due to coronary thrombosis. Intravenous thrombolytic agents were administered early in their presentation. Cardiac catheterization in two of the patients revealed normal coronary arteriography and in the third patient confirmed an aortic dissection. The patient with an aortic dissection died while the other two recovered without adverse consequences of the thrombolytic agents. Prior reports of five patients, treated with intravenous thrombolytic agents for suspected coronary thrombosis, who proved to have a final diagnosis of pericarditis or aortic dissection are reviewed. Death or tamponade occurred in four of five. The consequences of inadvertently administering intravenous thrombolytic agents to patients with nonthrombolytic cardiac disorders can be serious. If the diagnosis of acute myocardial infarction due to coronary thrombosis is uncertain, serial electrocardiograms, bedside echocardiography, or urgent cardiac catheterization may be appropriate before administering these agents.