The average urinary output in a series of 92 male schizophrenic patients was 2532 cc., that of 26 presumably healthy control subjects 1328 cc.Restrictions of water intake to about 1900 cc. of water both as such and in food in 10 of the patients with very high urinary output resulted in no particular complaints of thirst on their part although they did complain of the sameness and amount of food.It has been shown that the kidneys of schizophrenic patients are able to concentrate and dilute urine within normal limits in response to the ingestion of one litre of water.The anti-diuretic effect of obstetrical pituitrin is as effective in schizophrenic patients as in normal subjects reported in the literature.Further studies on the cause or causes of polyuria in schizophrenia are indicated.Abstract Teaser