In the present study, changes in the cytokine system (IL-1 beta, IL-2, IL-3, IL-6 and TNF alpha) were assessed following exposure to mild mood induction (negative and positive) in humans. An increase in secretion of TNF alpha, a decrease in that of IL-2 and of IL-3 with no change in IL-1 beta and in IL-6 secretion levels, was observed in response to mild negative emotional changes. A reversed cytokine secretion profile was found following positive mood changes, suggesting the hypothalamic-pituitary-adrenal axis and the autonomic nervous system, as possible mediators underlying these effects, specific to the nature of the emotion.