Bone marrow endothelial cells (BMECs) are an integral part of the bone marrow microenvironment and are likely to play an important role in the regulation of hematopoiesis, either by producing growth factors or inhibitory cytokines or by displaying adhesion molecules that can interact with hematopoietic progenitors. In the present study we demonstrate the isolation, propagation, and characterization of BMECs with regard to morphology, growth characteristics, phenotype, and production of cytokines. Furthermore, we report the creation of a cell line with "BMEC-like" characteristics and compare the characteristics of primary BMEC cultures to those of the immortalized cell line. In addition, we demonstrate that BMECs are susceptible to infection by a laboratory strain of human cytomegalovirus (CMV), suggesting that CMV infection of endothelial cells in vivo could potentially play a role in the hematologic abnormalities observed during CMV infection.