Angiogenesis is a multistep process of the development of capillaries from established blood vessels. Angiogenesis probably plays a significant role in the development and progression of hematopoietic malignancies. Higher microvascular density and increased serum levels of proangiogenic factors such as vascular endothelial growth factor (VEGF) or basic fibroblasts growth factor (bFGF) have been reported in acute and chronic leukemias, myeloproliferative and myelodysplastic disorders, multiple myeloma and lymphomas. The microvessel density of bone marrow stroma in myeloproliferative disorders is increased and VEGF is considered as the most potent endothelial cell activator. The purpose of this study was to examine the expression of VEGF in bone marrow of patients with MPD. 60 paraffinembedded bone marrow core biopsy specimens from newly diagnosed patients with MPD were evaluated. In addition 10 bone marrow core biopsy specimens from adult patients without evidence of malignancy were used as controls. Bone marrow sections were stained immunohistochemically for VEGF (PharMingen, USA). Obtained data show that MPD are associated with an increased expression of VEGF in the bone marrow. This observation support previous studies suggesting that angiogenesis may play a role in the pathophysiology of myeloproliferative disorders. Clinical significance of this phenomenon needs further investigation however thus provides rationale for use of angiogenesis inhibitors in MPD therapy.