We have studied the effect of phenotropil on the level of cytokines IL-1, IL-4, and IL-6 under conditions of immunosuppression induced by cyclophosphamide (150 mg/kg, single i.p. injection) and under immune system hyperreactivity caused by lipopolysaccharide (LPS of Pseudomonas aeruginosa, 100 gg/kg, single i.p. injection). The experiments were performed on 48 Wistar male rats aged 6-8 months. Each series was carried out according to similar schedule onree groups of animals: group 1, intact animals; group 2 received cyclophosphamide (series 1) or LPS (series 2); group 3 received phenotropil on the background of immunomodulators. Phenotropil (synthesized at the Department of Organic Chemistry of the A. I. Herzen St. Petersburg Pedagogical University) was administered in a dose of 25 mg/kg (i.p.) for 5 days, starting 2 days before the introduction of immune system activity modulatos. The levels of serum cytokines IL-1β, IL-4, and IL-6 were determined by ELISA "sandwich" with the use of monoclonal antibodies (ELISA kits of BenderMedsystems company; instrument Uniplan AIRF-01 of Picon company, Moscow) at a wavelength of 450 nm. In case of immunodeficiency caused by cyclophosphamide, there was a significant decrease in IL-1β, IL-4 and IL-6, but the introduction of phenotropil largely restored their levels. Upon stimulation with LPS, the immune response showed inc- rease in pro-inflammatory cytokines IL-β, IL-6 and decrease in IL-4. Under these conditions, phenotropil restored the normal levels of IL-1β, IL-6 and caused an increase in the level of IL-4.