The effects of tuftsin and its analogue TP-1 (300 micrograms/kg) on the animal adaptive behaviour in emotionally different situations, the level of biogenic amines and their metabolites 10, 30 min., 2 and 6 hrs after injection of these substances were studies. The TP-1 induced an increase in the memory traces stability better than tuftsin in emotionally negative situation. A single injection of the peptides induced changes in NA, DA and their metabolites contents for 30 min. to 2 hrs. In contrast to tuftsin, the TP-1 activated the metabolism of 5-HT in the hypothalamus and caudal brainstem without changing the NA turnover. The data obtained suggests that a stronger psychotropic activity of the TP-1 seems to be caused by its obvious effect on biogenic amines and their metabolites level in the brain.