A patient is presented with diabetes insipidus secondary to craniofacial trauma. Diabetes insipidus can occur in any patient within ten days of craniofacial trauma. Even the masked disease in the unconscious patient can be diagnosed by observation of intake and output, urinary specific gravities, and appropriate chemical studies. The disease can recur following operative reduction of facial fractures. Diabetes insipidus can be successfully treated by intramuscular Pitressin and appropriate fluid intake.