An interesting aspect of infection with several infectious agents is the possible association with some diseases apparently not associated with infections. One of the most exciting examples of this is the association of cardiovascular diseases with infection involving several different infectious agents. Cytomegalovirus (CMV) is one of the chief candidates that have been studied. Several epidemiologic reports indicate a possible association of various forms of vascular disease with the presence and titer of viral antibodies. Other studies show the presence of virus, viral antigens or nucleic acid in atherosclerotic lesions. Studies in animal models and cell-culture studies present attractive mechanisms by which the virus may play a role in the etiology of these diseases. However, negative results have also been reported, and more research is needed before the final verdict on this exciting question is presented.