Introduction. The development and introduction of new drugs with immunomodulatory effects is one of the priorities of modern medicine. Numerous studies have proven the immunotropic activity of individual substances isolated from medicinal plants (flavonoids, phenylpropanoids, polysaccharides, ecdysteroids, terpenoids, etc.). In this study, it is of interest to determine the immunomodulatory effect of individual substances isolated from Rhaponticum uniflorum (L.) DC. The purpose of the study. Determine the immunomodulatory properties of 20-hydroxyecdysone, 5-О-caffeoylquinic acid and arabino-3,6-galactan, isolated from the aerial part of Rhaponticum uniflorum (L.) DC, in relation to the cellular and humoral components of the immune response during exper-imental immunosuppression caused by cyclophosphamide. Material and methods. The experiments were performed on 100 male mice of the F1 line (CBAxC57Bl/6) weighing 18-20 g. Immunodeficiency was simulated by in traperitoneal administration of cyclophosphamide at a dose of 250 mg/kg once. The experimental group of animals received individual substances intragastricallyin the following doses: 5-О-caffeoylquinic acid - 10 mg/kg, arabino-3,6-galactan - 10 mg/kg, 20-hydroxyecdysone - 3 mg/kg, once a day for 14 days. The intact group of mice received purified water according to the analogous scheme. The state of humoral chain of the im-mune response was estimated according to the quantity of antibody-forming cells (AFC) determined with the use of Cunningham's plaque assay (1965). The state of the cellular chain of the immune response was estimated according to the delayed hypersensitivity reaction. Study results. It has been established that 20-hydroxyecdysone, 5-О-caffeoylquinic acid and arabino-3,6-galactan, isolated from the aerial part of Rhaponticum uniflorum (L.) DC, have immunomodulatory effect on the cellular and humoral components of the immune response in immunosuppres-sion caused by cyclophosphamide. Conclusions. The obtained results argues the feasibility of further research of individual substances, isolated from the aerial part of Rhaponticum uni-florum (L.) DC, with a view to creating new effective immunomodulators of plant origin.