Experimental data on the role of immunomodulators in the mechanisms of neurological memory are presented and assessed from the point of view of functional systems theory. It is demonstrated that the immunomodulator interleukin-1 beta and the alpha-2-interferon fragment RITLY improve the processes of learning and reproduction of an active defensive habit. These substances were found to have effects on the productivity of behavior, on orientational-investigative reactions, and on vocalization in response to a conditioned signal. A positive correlation between intersignal activity and productivity is demonstrated as a reflection of the mechanisms of anticipatory reorganization of behavior during learning. However, interleukin has a selective action depending on the ethological conditions obtained during learning.