The aims of this study are to determine the incidence and risk factors of thrombosis and bleeding in polycythemia vera (PV) patients and to research the effects of these risk factors on survival. The medical records of 155 PV patients were analyzed retrospectively. Patients were divided into groups according to whether or not thrombosis had developed in follow-up, and according to whether or not bleeding had occurred during follow-up. The mean age at diagnosis was 53 years, and the mean follow-up period was 66 months. The percentage of cases in which thrombosis events had occurred before diagnosis and during follow-up were 26 and 28 %, respectively. Comparisons of disease duration and average thrombosis risk score between groups with or without thrombosis drew statistically significant results. A patient's history of thrombosis and thrombocytosis at first visit was found to have a significant effect on thrombosis recurrence. The major bleeding rate was 8 %. Post-PV myelofibrosis was an independent risk factor for bleeding. The major cause of death among the patients in this study was primary thrombosis. The most important causes of mortality among PV patients are thrombosis, and the most prominent risk factors for thrombosis development are disease duration and high thrombosis risk scores. Thrombocytosis in patients with a history of thrombosis may cause thrombosis recurrence during the follow-up period.