The use of antibiotics during pregnancy and lactation is associated with an increased risk of developmental disorders. One of the natural medicinal plants-Rhodiola kirilowii, widely used as an immunostimulant in adults-might be a good alternative to antibiotic treatment. The aim of present study was to assess whether daily oral administration of 20 mg/kg of Rhodiola kirilowii aqueous (RKW) or 50% hydroalcoholic (RKW-A) extracts affected hematological and immunological parameters of 6-week-old mouse progeny. There was no significant change in hematological parameters of blood with the exception of hemoglobin, which was significantly higher (about 4%) in RKW group. Offspring of mothers fed Rhodiola kirilowii extracts had increased percentage of granulocytes and decreased percentage of lymphocytes. These changes correlated with decreased percentage of CD3+/CD4+ T-cells (RKW and RKW-A), decrease of CD8+ cells, and increase percentage of NK cells in RKW group. In addition, both types of Rhodiola kirilowii extracts stimulated granulocyte phagocytosis and increased level of respiratory burst. In conclusion, the long-term supplementation of mouse mothers during pregnancy and lactation with RKW or RKW-A extracts affects the immune system of their progeny. These results should be taken into consideration before administration of Rhodiola kirilowii to pregnant and lactating women.