Cerebral salt wasting syndrome is a hyponatremic and hypovolemic condition caused by intracranial disorders, such as head injury, subarachnoid hemorrhage, brain tumor, and brain operations. We report a case of a 5-year-old girl that had cerebral salt wasting syndrome with marked polyuria who showed transient oliguria during general anesthesia. The patient had undergone an operation for traumatic intracranial hemorrhage three months prior and has had marked polyuria and hyponatremia since then. After induction of anesthesia for cranioplasty, the patient had oliguria during surgery and then resumed polyuria in the post-operative period.