Rats were irradiated with γ-rays (30 Gy) and spontaneous behavioral activity in an ″open field″ as well as formation of conditioned reflex of adversive behaviour were registered in 1, 7-8 and 24 hr after exposure. The statistically verified depression of behavioral activity was found 24 hr after irradiation, while the prolongation of the latent period of conditioned reflex occurred as early as 1 hr after irradiation. The results obtained are discussed from the point of view of GABA-system involvance in the changes observed.