Waking noncurarized rabbits were subjected to defensive conditioning. Subcutaneous injections of GABA derivative conditioning. Subcutaneous injections of GABA derivative Phenibut (nootropic) (40 mg/kg) were shown to accelerate the acquisition of internal inhibition, to decrease and stabilize the time of intersignal reactions, to increase the heart rate, and to decrease the respiration rate. At the early stage of conditioning, Phenibut facilitated movements in response to a conditioned stimulus. Consequently, when using nootropics for normalization and improvement of the CNS operation, one should take into account their effects not only on excitation but also on inhibition in the CNS, as well not only on cognitive processes but also on the somatic state. The findings confirm the involvement of GBABergic neurotransmitter system in the internal inhibitory conditioning.