The major patterns of erythrocytosis (poycythemia) are secondary and relative forms. These clinical entities of erythrocytosis are much variable in their causative factors and need to be differentiated with poycytemia vera. To the best of our knowledge, systematic reviews of erythrocytosis in Korea are absent with the exception of several clinical reports of polycythemia vera. Twenty-seven cases of erythrocytosis during 13 years from 1975 to 1987 in Severance Hospital, Yonsei university were studied.
In 27 cases of erythrocytosis, polycythemia vera, secondary polycythemia, and relative polycythemia were 9 cases, respectively. Patients of relative polycytemia were all male. As a causative diseases of secondary appropriate polycythemia, 2 cases had chronic obstructive lung disease, 1 congenital heart disease(TOF) ; 3 cases had cystic renal
disease, 2 hepatoma and 1 undetermined cause of secondary inapproprite polycythemia. In patients of relative polycythemia, 4 cases had history of hypertension, 3 cases of smoking and drinking with hypertension as a stress polycythemia ; 2 cases were polycythemia of dehydration.
The major complications of erythrocytosis were cerebrovascular diseases comprising approximately 22% and 33% of secondary and relative polycythemia, in association with hypertension in 67% and 78%, respectively. Mortality cases were 1 in polycythemia vera who died from renal and hepatic vein thrombosis, 2 in secondary polycythemia from
congestive heart failure and hepatoma.
These observations emphasize the need for a full attention to the more active diagnostic approaches and more intensive therapeutic modalities in patients with any types of polycythemia because of clinically malignant nature in polycythemia vera, and possibly implicated vascular complications in secondary and relative polycythemia.

Keywords: Erythrocytosis(Polycythemia), Phlebotomy, Erythrapheresis,