The term "désinhibition" has a different meaning for the psychopharmacologist and for the psychiatrist. The action of anti anxiety agents on animal behavior is described with a special interest for the passive and active avoidance tests. The mode of action and the site of action of benzodiazepines is discussed, focussed on the existence of an endogeneous ligand displacing the binding of diazepam. The differences between low and high doses of anti-anxiety agents are stressed in patients and normal volunteers, and the treatment of inhibition by benzodiazepines is also discussed.