Three children with diabetes insipidus, diabetes mellitus, optic atrophy, and high-tone deafness were shown to lack vasopressin, indicative of degeneration of the cells of the hypothalamic supraoptic nuclei. The syndrome being due to a single gene defect, inherited as an autosomal recessive, is therefore likely to be the result of an inborn error of metabolism with variable periods of latency in those affected.