Two new cases of Wolfram's syndrome associated with progressive urinary tract dilatation are reported. The possibility of anatomic outlet obstruction or neurogenic bladder was eliminated radiologically and urodynamically. Dilatation of the urinary tract was considered to be a consequence of high diuresis associated with diabetes insipidus. A very important improvement in bilateral urinary tract distension was achieved with bladder drainage while dDAVP therapy dramatically decreased the daily urinary output. A review of diabetes insipidus and its urological implications is presented.