Recombinant human growth hormone (rhGH) administered to combination antiretroviral therapy (cART)-treated human immunodeficiency virus-1 (HIV-1)-infected individuals has been found to reverse thymic involution, increase total and naïve CD4 T-cell counts, and to reduce the expression of activation and apoptosis markers. To-date, such studies have used high, pharmacological doses of rhGH. In this sub-study, samples from treated HIV-1(+) subjects, randomised to receive either a physiological dose (0.7mg) of rhGH (n = 21) or placebo (n = 15) daily for 40 weeks, were assessed. Peptide-based ELISpot assays were used to enumerate HIV-1-specific IFN-γ-producing T cells at baseline and week 40. Individuals who received rhGH demonstrated increased responses to HIV-1 Gag overlapping 20mer and Gag 9mer peptide pools at week 40 compared to baseline, whereas subjects who received placebo showed no functional changes. Subjects with the most robust responses in the ELISpot assays had improved thymic function following rhGH administration, as determined using CD4(+) T-cell receptor rearrangement excision circle (TREC) and thymic density data from the original study. T cells from these robust responders were further characterised phenotypically, and showed decreased expression of activation and apoptosis markers at week 40 compared to baseline. Furthermore, CD4 and CD8 T-cell populations were found to be shifted toward an effector and central memory phenotype, respectively. Here we report that administration of low-dose rhGH over 40 weeks with effective cART resulted in greater improvement of T-lymphocyte function than observed with cART alone, and provide further evidence that such an approach may also reduce levels of immune activation.