Objective: Treatment-naïve patients with human immunodeficiency virus (HIV) are characterized by diffuse abnormalities of resting-state cortical electroencephalographic (EEG) rhythms (Babiloni et al., 2012a). Here, we tested the hypothesis that these EEG rhythms vary as a function of the systemic immune activity and antiretroviral therapy (ART) in HIV patients. Methods: Resting-state eyes-closed EEG data were recorded in 68 ART-HIV patients (mini mental state evaluation (MMSE) of 27.5. ±. 0.3 SEM), in 60 treatment-naïve HIV subjects (MMSE of 27.5. ±. 0.4 SEM) and in 75 age-matched cognitively normal subjects (MMSE of 29.3. ±. 0.1 SEM). Based on the CD4 lymphocytes' count, we divided ART-HIV subjects into two subgroups: those with CD4. >. 500. cells/μl (ART-HIV+) and those with CD4.