Two cases of lymphocytic hypophysitis are reported, in which hypothalamic involvement causing diabetes insipidus was a prominent clinical feature. In one case, a man had clinical and radiological evidence of the involvement of the cavernous sinus. This represents the second reported case of a man with lymphocytic hypophysitis. A transsphenoidal biopsy established the diagnosis in both cases. Neither the involvement of the cavernous sinus nor permanent diabetes insipidus has been reported previously. A review of the literature is provided.