The aim of the study was to determine the effect of chronic unpredictable stress (CUS) and maternal mirtazapine treatment on the pro-inflammatory cytokines IL-6 and TNF-α in the plasma of dams and their adolescent offspring (PP50) of both sexes.In the present study, mothers (n = 6-8/ group) and adolescent offspring (n = 6-8/ group) were divided into 4 groups: no stress+vehicle, no stress+mirtazapine, stress+vehicle, stress+mirtazapine. Dams in the stress group were exposed to CUS for a total of 3 weeks. Females from each group were then mated and treated from the 10th day of gestation to the 21th postnatal day with mirtazapine (10 mg/kg/day) or vehicle (water). For IL-6 and TNF-α determination were used commercial ELISA kits.Measurement of IL-6 plasma concentration by ELISA showed a significantly increased concentration in vehicle and treatment group of stressed dams. We did not observe a difference between the non-stress and stress-group groups in adolescent males and females. The concentration of TNF-α was significantly lower only in no-stress mothers with mirtazapine. In adolescent offspring, we observed significantly lower plasma levels in stressed males with vehicle, while we did not show any changes in adolescent females.These results suggest that changes in plasma concentrations of IL-6 and TNF-α can be dependent on chronic stress and treatment. Further studies are needed to explain the changes in TNF-α in adolescent males.Acknowledgement: Study was supported by the grants APVV-19-0435 and VEGA 2/0133/23.