Eight cases of convulsive coma by water intoxication without predisposing disease in the majority of instances in psychiatric patients, added to 25 cases from the literature make it possible to describe a stereotyped picture of "psychogenic" water intoxication. This includes episodes of polydipsia preceding convulsions and altered conscious level, accompanied by severe hyponatraemia. Cure occurs spontaneously after an acute hypotonic polyuric phase. Study of free water clearances and dynamic ADH suppression tests demonstrate hypovasopressinism which is difficult to inhibit, with "lower osmoreceptor reset". This abnormality is transient and sometimes relapsing.