In healthy blood donors, serological positivity for human cytomegalovirus (HCMV) is associated with an increased proportion of NK cells bearing the CD94/NKG2C NK cell receptor (NKR). The expression of the activating CD94/NKG2C NKR and of the inhibitory CD94/NKG2A NKR was studied in a cohort of 45 aviremic human immunodeficiency virus type 1 (HIV-1)–positive patients receiving highly active antiretroviral therapy. The proportions of NKG2C⁺ NK cells were significantly increased in HIV-1–positive patients (mean±SD, 25.9%±23.0%), compared with those in 31 healthy individuals (mean±SD, 16.1%±20.7%). Yet, the association vanished when HCMV serological status was considered in a multivariate regression model. These results support the conclusion that changes in the NKR repertoire in HIV1–positive patients are related to a concomitant HCMV infection