Diabetes mellitus and bilateral optic atrophy are the defining characteristics of the autosomal recessive Wolfram syndrome. Diabetes insipidus, neurogenic bladder, deafness, and other neurological manifestations are frequent. A review was made of the medical records of 68 Wolfram syndrome patients, aged between 8 and 43 years, identified by casefinding throughout the USA. 41 of the patients (60%) had episodes of severe depression, psychosis, or organic brain syndrome, as well as impulsive verbal and physical aggression. These symptoms were very severe in 17 patients (25%), of whom 12 required admission to a psychiatric hospital and 11 attempted suicide. We conclude that the Wolfram syndrome gene predisposes homozygotes to psychiatric illness.