The author distinguishes inhibition as a symptom from inhibition as a processus in the three following situations: a) Antidepressants and melancholic inhibition: the action on inhibition is studied referring to Kielholz classification of antidepressants. The author points out the risk of suicide by suppressing inhibition. b) Antidepressants and chronical psychoses: the author compares effects of antidepressants and stimulating neuroleptics in these syndroms. He thinks that with the two types of psychotropic drugs, one can obtain a desinhibitory effect. But antidepressants can be better used in paranoid personnalities, loss of ego boundaries, and some schizophrenic-like syndroms, when neuroleptics seem to be more desinhibitory in hebephrenics. The author stresses the depressive core in these psychotic personnalities. c) The antidepressant effect has been studied in neurotic depressions. The author describes essentially cases with reinforcement of inhibition as a negative therapeutic reaction by antidepressants. It deals with neurotic depressions evoluting on narcissic personnality back ground.