Cytomegalovirus (CMV) infection is a substantial cause of morbidity and mortality among immunocompromised patients. It may present with a mild, self-limited syndrome, retinitis, colitis, or invasive disease with pneumonitis, hepatitis, and bone marrow suppression. We review another, less common manifestation of CMV disease: CMV-associated vasculitis. CMV may productively infect vascular endothelial cells (25), causing a local vasculitis (3, 14, 19) and ischemia. Alternatively, the host immune response to cells expressing viral antigen may be the stimulus for vasculitis (12, 53). Since there are no pathognomonic appearances to mucosal or cutaneous lesions, biopsy of accessible sites is critical for diagnosis and expeditious initiation of appropriate antiviral therapy. The CMV-associated vasculitides represent a broad spectrum of diseases, with GI vasculitis in nontransplant recipients having the best prognosis. Cutaneous vasculitis associated with CMV seems to be a more fulminant disease, with the majority of cases having a fatal outcome. These differences likely reflect the degree of viral burden and the state of immune competence. Additionally, since the virus itself is immunosuppressive, host defenses may be further compromised by the infection. Although a large collective experience assessing the impact of ganciclovir and foscarnet is not currently available, both the prompt initiation of antiviral treatment and a concurrent reduction in any immunosuppressive regimen, including steroids, should be undertaken since these therapeutic strategies have clearly improved outcome for other CMV syndromes (22, 34, 55). As the number of recipients rises and the HIV pandemic spreads we are likely to see an increase in the number of cases of vasculitis associated with CMV infection.(ABSTRACT TRUNCATED AT 250 WORDS)