To evaluate the potential clinical utility of a cytomegalovirus (CMV)-specific CD8+/interferon (IFN)- gamma+ cytokine flow cytometry (CFC) assay for patients with CMV retinitis (CMVR), stored peripheral blood mononuclear cell specimens were obtained from patients with active CMVR (i.e., having clinical evidence of absent CMV-protective immunity), as well as from highly active antiretroviral therapy-treated patients with CMVR who were able to discontinue anti-CMV therapy without subsequent progression of retinitis (i.e., having clinical evidence of restored CMV-protective immunity). Positive CD8+/IFN- gamma+ T lymphocyte responses to CMV phosphoprotein 65 or immediate early peptide-pool stimulation were present in specimens from only 3 of 10 patients with active CMVR but were present in at least 1 specimen from all 20 patients with immunorestored CMVR, with a mean of 2.4 specimens/patient tested, spanning up to 6 months of observation (P = .0001). Among the patients with immunorestored CMVR, positive responses were present in all longitudinal specimens from 15 of the 20 patients. These data suggest that further testing of the CMV-specific CD8+/IFN- gamma+ CFC assay, for clinical utility in predicting incident and progressive CMVR disease, is warranted.