In rats, antisera to neurospecific protein S-100 (matrix solution) in doses 1–5 ml/kg and diazepam 2 mg/kg i.p. produced anxiolytic effect in the open field and elevated plus maze tests. Besides, in rats reared in community, antisera to neurospecific protein S-100 5 ml/kg and amphetamine 1 mg/kg activated the self-stimulation reaction increasing the number of pedal pressings by 1.5 fold. In rats reared in social isolation since 17th day of life and being alcoholized within 3 months, both antisera to neurospecific protein S-100 in dose range 2.5–10 ml/kg and amphetamine 1 mg/kg induced psychoactivating effect. In is concluded that antisera to neurospecific protein S-100 possess both psychoactivating and anxiolytic effects as do tranquilonootropic drugs.