Essential thrombocythemia (ET) is a myeloproliferative neoplasm characterized by a clonal expansion of megakaryocytes. ET can result in both arterial and venous thrombosis. Involvement of the coronary arteries has been reported. Patients who harbor a CALR mutation are half as likely to suffer a thrombotic event as compared to patients with a JAK2 mutation. We report a case of CALR-mutated ET whose initial disease manifestation was a non-ST segment elevation myocardial infarction.