Essential thrombocythemia (ET) rarely causes obstruction of coronary arteries or acute myocardial infarction. Treatment of acute myocardial infarction in patients with ET may be a problem due to the important role of platelets in the pathogenesis of infarction. There is no reported case of acute myocardial infarction with essential thrombocythemia treated with a glycoprotein IIb/IIIa inhibitor. In this report, a 49-year-old woman with essential thrombocythemia, admitted with a diagnosis of acute inferolateral myocardial infarction, was treated with tirofiban, a glycoprotein IIb/IIIa receptor blocker.