The anxiolytic effect of Proproten containing potentiated antibodies to brain-specific S100 protein (2.5 ml/kg) in male outbred albino rats was studied under conditions of punished (Vogel's conflict situation with pain stimulation) and unpunished behavior (elevated plus-maze and open-field tests). Proproten significantly increased the incidence of punished drinking in the conflict situation with pain stimulation, number of entries, and time spent in the open arms of the elevated plus-maze and decreased the rate of defecation and urination. In the open-field test Proproten induced entries of rats into the center of an illuminated area. Proproten was efficient after single administration and course of treatment (2 times a day, 5 days). These results show that Proproten produces the anxiolytic effect under conditions of punished and unpunished behavior.