Eight patients with polycythemia vera were diagnosed from 1965 through 1977 among the patients of Seoul National University Hospital. In our series there were 4 men and 4 women with average age of 54 years at the time of diagnosis. Symptoms of facial plethora, headache, pruritus and dizziness were the most frequent manifestations of disease in order of frequency. At inital examination 8 of 8 patients had facial plethora, 6 of 8 patients splenomegaly and 4 if 8 patients hepatomegaly. The laboratory data revealed mean Red cell volume of 55+10ml/kg which was elevated in all cases. Leukocytosis was observed in 5 of 8 patients and thrombocytosis 2 of 8 patients. Leukocyte alkaline phosphatase was increased in all cases. Bone marrow aspiration disclosed typical panmyelosis in 5 of 8 patients. In one patient there was diffuse myelofibrosis on bone marrow biopsy. The combined diseases included 2 patient with hypertension and 1 patient with thrombosis of aorta and left renal artery. The patients were treated with phlebotoany alone in 2 patients, chemotherapy with busulfan in 1 patient and 32P in 5 patients with favorable results. During the mean 29.9 months follow up period, there were development of iron deficiency in 3 patients, hyperuricemia in 2 patients and thrombosis in 1 patient. The occurrence of acute leukemia of myelofibrosis was not observed in the course of disease.