JAK2V617F is a novel oncogene involved in myeloproliferative neoplasms (MPN) and closely related to its vascular complications. Recent researches found the vascular endothelial injury in patients with MPN. It is increasingly being recognized that endothelial cells and endothelial progenitor cells (EPC) play an important role in MPN. Here, the pathogenesis of the EPC JAK2V617F mutation and peripheral blood EPC counts in patients with MPN or with vascular complications are reviewed.