The cytokine status (IFN, IL, etc.) of different monkey species (M. mulatta, P. hamadryas, C. aethiops) was studied. The interferon status is determined by the following parameters: IFN content in circulating blood and production of IFN-alpha and IFN-gamma by lymphocytes after appropriate in vitro induction. The interferon status of monkeys is similar to that of humans. The capacity to produce IFN reduces with age. It was found that genes of virtually all studied cytokines are expressed in blood cells and hence, in immune system cells.