The biological properties of human cytomegalovirus are consistent with pathogenic involvement at several levels of the atherogenic process. Although the sites of latency of CMV have not been established, both smooth muscle cells and leukocytes are likely possibilities. The observations of viral antigens and nucleic acid sequences in arterial smooth muscle cells suggest that latent CMV infection of the arterial wall may be common in patients with atherosclerosis. The seroepidemiologic studies suggest that a periodically activated latent infection is present in patients with atherosclerosis. Important are the observations that in immunosuppressed heart transplant patients infected with CMV, atherosclerosis is prone to develop in the transplanted heart. This mainly circumstantial evidence of the involvement of CMV in human atherosclerosis provides an important basis for further investigation of the role of CMV in atherogenesis.