AD169, a well-characterized laboratory strain of human cytomegalovirus (HCMV), was used to establish an animal model of progressive HCMV chorioretinal disease by injection of 105 pfu into the rabbit vitreous. Chorioretinal, vitreous, and pulmonary disease were monitored by HCMV recovery, clinical observation, antigen localization, and histopathology. Vitritis and focal areas ofimmune cellular infiltrates were seen in inner retinal layers on days 2-4 after inoculation. Disease progressed with more severe vitritis and to involve the outer retinal layers in areas of mixed monocytic cellular infiltrates, retinal destruction, choroidal edema, and congestion. HCMV was recovered from chorioretinal cell sonicate cultures in titers ranging from 104 to 105 pfu during peak disease, and HCMV antigens were detected focally by immunofluorescence in retinal layers on days 2 and 4 after inoculation. A rabbit model of HCMV chorioretinitis similar to human CMV disease allows investigation of HCMV pathogenesis and new antiviral therapies and evaluation of immune system modulation of the HCMV ocular infection. © 1993 by The University of Chicago.