The aim of the present work was an estimation of the influence of two plant pharmaceutical preparations containing an extract from the root of Eleutherococcus senticosus: Argoeleuter tablets and Immuplant tablets, on the humoral response of immunological system. Experiments were performed with female Balb/c mice six weeks old. In order to reveal the influence of taking preparations, containing an extract from Eleutherococcus senticosus on some elements of the immunological system, three ways of their administration have been compared: before illness, during illness and a combination of both. The obtained results allow formulating the following conclusions: - the pharmaceutical preparations, containing the extract from Eleutherococcus senticosus administered orally, influence on the increase of the level of immunoglobulins comprised in the mice's blood serum, - the pharmaceutical preparations act with different power, not fully dependent on the content of marker of the active substance - eleutheroside E, - dosage of the preparations containing the extract from Eleutherococcus senticosus should not be established basing only on the extract content, - best curative results, measured as the stimulation of humoral response of the organism were obtained when a given preparation was administered therapeutically, even though the combined administration - prophylactically with prolonged administration during illness also is correct.