Diabetes insipidus is a life-threatening condition in which the kidneys excrete huge quantities of diluted urine. Diabetes insipidus as a sequela of head trauma is unusual, but not rare. When it arises in conjunction with a spinal cord injury (SCI), diabetes insipidus not only is life threatening but also raises challenges for bladder retraining. This article describes the pathogenesis, diagnosis, and management of diabetes insipidus. A case study is used to demonstrate the patient course and nursing implications, with emphasis on two nursing diagnoses: fluid volume deficit and alterations in urinary elimination.