After a brief review of the most important papers published with regard to Haloperidol the authors report their own experience in the treatment of 82 interned patients, mostly schizophrenics. In most cases treatment began with a daily dosis of 1 mgm., and was gradually increased until maximum doses varying between 3 and 16 mgm. They came to the conclusion that Haloperidol has a clear sedative and hallucinolytic effect and is indicated especially in the treatment of patients with mania and paranoid schizophrenia, as well as in other psychoses with a predominating psycho-motoric agitation and/or delirating-hallucinatory syndrome. Hebephrenic and catatonic forms of schizophrenia did also improve with this treatment. As to side effects, most patients presented an impregnation-syndrome (akineto-hypertonic syndrome) and almost all of them insomnia; some showed acathisia; in only one case intense autonomic disturbances were observed in the cardiovascular system. Diffuse electroencephalographic changes which disappear after completion of treatment are described.