en case report case report Essential thrombocythemia is a chronic myeloproliferative disorder characterized by a sustained proliferation of megakaryocytes, which leads to increased numbers of circulating platelets. Hemorrhagic and/or thrombotic episodes are frequent, and thrombosis of both veins and arteries may develop. Vessels in unusual sites may be involved, e.g., the hepatic veins, mesenteric veins, and the digital vessels. Thrombosis of the inferior vena cava has not been reported previously. In this paper we report inferior vena cava thrombosis in a patient with essential thrombocythemia. 167 169 http://mjiri.iums.ac.ir/browse.php?a_code=A-10-298-476&slc_lang=en&sid=1 J EIVAZI ZIAEI 20031947532846006867 20031947532846006867 Yes From the Dept. of Hematology, Gazi Hospital, Tabriz University of Medical Sciences, Tabriz, Islamic Republic of Iran.