The role of lysine-vasopressin and oxytocin, as well as of their analog and fragment (DGAVP, desglycinamide arginine vasopressin; PLG, prolyl-leucyl-glycyl-amine), microinjected into the ventral hippocampus, in the formation and extinction of active avoidance conditioned reflex, was investigated. It was established that the introduction of lysine-vasopressin, as well as of its analog, into the hippocampus promoted the improvement of the formation of the avoidance reaction, while an inhibitory effect was elicited in the period of extinction of the skill. The opposite effects on the active avoidance reaction were obtained with oxytocin and its fragments. It is hypothesized that the observed behavioral changes in the active avoidance reaction are associated with the influence of these peptides on the processes of learning and memory.