Microglial cells and astrocytes isolated from human embryonic proencephalon were compared to monocyte-derived macrophages (MDM) for their ability to replicate human cytomegalovirus (HCMV) in vitro. A specific cytopathic effect was observed in microglial cells and astrocytes, but not in MDM. A high percentage of glial cells but a low percentage of MDM expressed immediate-early and late viral antigens. The ability of HCMV-infected microglial cells and astrocytes to release viral particles in their supernatants was significantly higher than that of infected MDM. Human microglial cells and astrocytes at an early stage of development are highly susceptible to HCMV infection.