Protective and antistress effects of three glyprolines--PGP, PG and GP, were studied. Stress influences produced typical changes of behavioural activity of rats in the elevated pluz-maze and the hole-board tests. These changes suggest a significant enhancement of anxiety and a drop of the level of orientation-investigative activity. A preliminary (15 minutes before stress agent) intraperitoneal administration of PGP or GP in doses of 3.7 microm/kg significantly decreased stress disturbances of behaviour. Analysis of these data shows to the possibility of PGP and GP influences on the CNS structures, which take part in the organism reciprocal reactions to stress factor. The peptide GP at equimolar dose didn't possess pronounced protective properties and just slightly decreased stress disturbance of behavioural activity of rats.