We describe three cases of cranial diabetes insipidus (CDI) caused by Wegener's granulomatosis (WG). Panhypopituitarism was the presenting symptom in one patient. Magnetic resonance imaging (MRI) showed enlargement of the pituitary gland with an intrasellar mass lesion and absence of posterior pituitary lobe hyperintensity. Follow-up MRI disclosed reduction of the intrasellar lesion but sustained loss of posterior lobe hyperintensity. The patients still have CDI despite a marked clinical response to the treatment of WG. Pituitary dysfunction may be the presenting symptom as well as a complication of WG.