Xanthomatosis, the Schüller-Christian syndrome, generally characterized clinically by the symptom triad of defects in the membranous bones, exophthalmos and diabetes insipidus, has been recognized as a systemic disease. Histopathologically, the disease is characterized by a diffuse collection of lipoid cells ("foam cells"), cellular reactions and fibrosis in various organs of the body. The granulomatous collections within the skull and dura mater giving rise to neurologic symptoms have been described frequently. The polyuria and polydipsia are believed to result from pressure on the hypophysis and tuber cinereum or from direct invasion of these structures by such lipoid masses. Although the lesions of the pituitary gland and tuber cinereum have been reported by a few observers, involvement of the rest of the neural structures, as far as could be ascertained, has not been recorded before. The neurologic and neuropathologic findings in this case were of sufficient importance to warrant a separate report.