The aim of the paper was to compare the periodical changes in serum cytokine levels and in cytokine production in short-term blood lymphocyte cultures of two persons: the patient with major depression and healthy control. In sera of both persons such cytokines as IL-1 beta, IFN-gamma and IL-6 were detected, but IL-6 level in serum of depressed patient was higher than that observed in healthy control. In both persons examined serum cytokine level changed periodically during 9 days of observation showing rhythmic waves. When cytokines were induced in lymphocyte cultures periodical changes in their production were also observed, but IL-1 alpha, IL-1 beta and IL-12 production was significantly lower in comparison to lymphocytes of healthy control. After 36 days of medical treatment cytokine levels in serum of patient normalized, except for IL-12. Our results suggest that inconsistence in the data from papers of different authors concerning cytokine production in major depression could result from periodical changes in their level and from the fact that patients were examined at the time when certain cytokine was near its peak or declined significantly. The rhythmic changes in cytokine level should be taken into consideration when the role of cytokines in major depression is examined.