This investigation tested the hypothesis that hypnosis can differentially modulate T-cell subsets, and that this effect is mediated by changes in hypothalamo-pituitary-adrenal (HPA) mediators. Seven healthy, highly hypnotizable volunteers participated in three one-day sessions, a baseline and two intervention sessions. Hypnosis intervention entailed a standardized induction, suggestions for ego strengthening and optimally balanced functioning of the immune and neuroendocrine systems, and post-hypnotic suggestions for stress management and continued optimal balance of bodily systems. Blood samples were drawn at five time points between 8:00 a.m. and 3:00 p.m. and were analyzed for T-cell activation and intracellular cytokine expression (Interferon (IFN)-gamma, Interleukin-2, Interleukin-4) and HPA axis mediators (ACTH, cortisol, and beta-endorphin). Following hypnosis intervention, statistically significant immunological effects were noted. Specifically, the proportion of T-cells expressing IFN-gamma (p = .0001) and IL-2 (p = .013) were lower after hypnosis. T-cell activation response to polyclonal stimulation was positively correlated with ACTH (p = .01) and beta-endorphin (p = .001) while IFN-gamma expression was correlated with levels of cortisol (p < .001). Further controlled studies utilizing hypnosis with patients in treatment are warranted in order to examine whether an altered T-cell response can be replicated in the presence of disease.