The influence of stress of various etiology (prolonged isolation, anavoidable electrostimulation, paradoxical sleep deprivation, transport stress) on the activity of anxiolytics (tranquilizers) in the conflict situation was studied in inbreed white male rats. It was established that the anticonflict effect of highly effective anxiolytics decreases under the action of stress, the activity of gidazepam remains unchanged, while the drugs of moderate efficacy loose their activity. The degree of changes and the rate of restoration of the initial activity depends on the efficacy of anxiolytics, the strength and duration of stress, and on the duration of drug administration after stress. The possible mechanism of this phenomenon can be the stress-induced activation of the endogenous system of anxiogenic ligands.