A study was carried out on 51 polycythemia vera patients based on the 2008 WHO diagnostic criteria. All of them was treated in the Blood transfusion and Hematology hospital of Ho Chi Minh city from October 2008 to September 2011. Most of these patients were from 45 to 59 years old. The most common clinical symptoms were ruddy cyanosis, conjunctival plethora, hypertension, headache, and vertigo. Peripheral blood smear demonstrated trilineage hyperplasia in 45 percent of cases. The JAK2V617F mutation was found in 98 percent of cases. The results of this study show that peripheral blood mutation screening for JAK2V617F plays an important role in diagnosis of polycythemia vera in early stage.