Background & objectives: Under the lymphopenic condition, T-cells divide to maintain their peripheral pool size. Profound chronic lymphopenia in some treated HIV-infected patients, characterized by poor T-cell recovery, might result in intensive homeostatic proliferation and can cause T-cell exhaustion and/or senescence. The present study was undertaken to evaluate the homeostatic proliferation of CD4+T-cells in treated HIV-infected individuals, and to determine the amount of phenotypically exhausted and senescent CD4 T-lymphocytes. Methods: Thirty seven treated HTV-infected patients with suppressed HTV viral load (<50 copies/ml) were studied. Patients were divided into two groups: immunological non-responders (INRs) with СD4 T-cells < 350/μl (n = 16) and immunological responders (IRs) with CD4 T-cells > 350/μ1 (n = 21). T-cell subsets [naive, central memory (CM), and effector memory (EM)] and proportions of cycling (Ki-67+), senescent (CD57+) and exhausted (PD-1+) T-lymphocytes were assessed using flow cytometry. Resutis: CD4T-cell cycling rate was higher in INRs than in IRs due to more extensive proliferation of CM, 4.7 vs 2.7 per cent (P < 0.01) and EM, 4.8 vs 3.2 per cent (P < 0.05). The percentages ot'C'D4 Ki-67 CM and EM Т-lymphocvtes were inversely related to the CD4+T-cell counts in the appropriate subset, r = -0.584 (P < 0.001) and r = -0.556, (P < 0.001), respectively. Exhaustion [24.2 vs 16.7 % (P < 0.001)], but not senescence [7.1 vs 10.8 % (P > 0.05)] was more pronounced in the INR group than in the IR group. The frequency of CD4+Ki-67+ CM T-cells was related to the proportion of CD4PD-1 cells of the same subset, r = 0.789 (Р < 0.001). The numbers of CD4 KI-67 PD-1 CM and EM T-cells were substantially higher in INRs than in IRs. Interpretation & conclusions: The present data indicated that intensive homeostatic proliferation contributed to the T-cell exhaustion in HlV-infection.