The case of a 28 year-old man in whom diabetes insipidus appeared 24 hours after Pantopaque myelography is reported. This unusual complication, not previously reported, probably was caused by a hypersensitivity reaction or mechanical-irritative effect on the hypothalamic-hipophyseal area produced by suprasellar Pantopaque droplets, demonstrated by skull x-rays. The patient improved after being treated with steroids. Some serious complications of myelography can be prevented by avoiding supratentorial spillage of Pantopaque.