In situ hybridization of human immunodeficiency virus-1 (HIV-1) has been performed on eight eyes from eight distinct acquired immune deficiency syndrome patients (three cases had a normal fundus examination and five presented with cytomegalovirus retinitis). The eyes were removed at autopsy and frozen immediately. Contiguous 10-mu cryostat sections were obtained and tested with a HIV probe labeled by nick-translation with [35S]-ATP. HIV-1 RNA was detected in the retina of two acquired immune deficiency syndrome patients. The first positive case presented with typical ophthalmological and histopathological cytomegalovirus retinitis, the second one was not related to cytomegalovirus, according to clinical or histopathological classical criterias. HIV-1 was localized in retinal vascular walls. This shows that there is an active replication of HIV in retina of some acquired immune deficiency syndrome patients.