Hypothalamic and pituitary tumours may present with vague symptoms owing to excess or lack of hormone production, including diabetes insipidus. Corticosteroids are commonly employed to limit cerebral oedema and at much lower doses to treat secondary hypocorticalism. Continuation of steroids at inappropriately high doses predisposes to the development of avascular necrosis as in the case we describe in a young woman of 34 years. This is a potentially preventable crippling disorder. When prescribing steroids the lowest effective dose should be used.