In a number of studies it has been shown that psychological factors in general and specifically emotional factors can be correlated to changes in immunological function and defence mechanisms. Although the mediating pathways between the central nervous system and the immune system still remain unclear, it is known that some of the‘classical stress hormones’such as cortisol and catecholamines have modulatory effects on different immunological parameters. In this investigation we wished to study the effect of brief hypnotically induced emotional States on monocyte chemotaxis and endocrinological parameters. Eleven highly hypnotically susceptible volunteers were, while in a deep trance, given suggestions to re-experience earlier life experiences involving intense anger and depression in random order. Before concluding hypnosis subjects were given suggestions to re-experience a feeling of happiness and well-being. Monocyte chemotactic activity in sera and serum levels of cortisol, as well as venous plasma levels of the catecholamines epinephrine, norepinephrine. DOPA and DOPAC. were measured before hypnosis, after each emotional stale and immediately after hypnosis. The results showed a significant difference (P<0.02) in chemotactic activity between the angry and the depressed emotional states, the depressed state exhibiting a decreased chemotactic index compared with the angry slate. Chemolactic index after the happy relaxed emotional state also showed a significant (P<0.01) increase compared with both chemotactic index before hypnosis and chemotactic activity after the angry and depressed state. Though there were significant differences between emotions and between emotions and the before-hypnosis-concision, no clear-cut significant differences between the emotional slates of anger and depression could be detected for serum cortisol levels and catecholamine plasma levels. Significant positive correlations (P<0.01) for differences in chemotactic activity and differences in plasma DOPA levels between emotional states was found. When investigated in vitro, DOPA did not in itself exhibit monocyte chemotactic properties. No other significant correlations between differences in chemotactic activity and other endocrinological parameters could be detected. Soluble interleukin-2 receptors in serum were also measured. No significant differences were found.