In order to document anterior pituitary dysfunction in patients with biopsy-proven Langerhans cell histiocytosis (LCH) and diabetes insipidus and to correlate this with structural changes on imaging, we performed an insulin tolerance test, enhanced computed tomography (CT), and unenhanced magnetic resonance imaging (MRI) in nine patients. Six of the nine patients had growth hormone deficiency, which in two patients was part of panhypopituitarism and in one was associated with poor cortisol response to insulin hypoglycemia. One patient had an exaggerated growth hormone response and one who had had neck irradiation as an infant, had a high resting thyroid stimulating hormone (TSH) suggesting compensated primary hypothyroidism. All enhanced CTs were abnormal, bony defects being the only abnormality in two patients and opaque mastoids in one. The remaining six patients all had structural changes in the hypothalamic/pituitary region. Unenhanced MRI confirmed the CT findings except in one child who had been treated with radiotherapy in the intervening period, but, in addition, confirmed diabetes insipidus by showing absence of the posterior pituitary bright signal and picked up white matter changes in a child with clinical neurological dysfunction. Our findings indicate that the development of diabetes insipidus in LCH is commonly associated with anterior pituitary dysfunction and is usually associated with structural changes in the hypothalamic/pituitary axis.