BACKGROUND: Lymphocytic adenohypophysitis is a well-known autoimmune disorder affecting the anterior pituitary gland. Posterior pituitary gland function can be impaired by a similar autoimmune disorder called lymphocytic infundibulohypophysitis. Only very few cases have been reported. CLINICAL PRESENTATION: We present a patient with central diabetes insipidus in the postpartum period. On radiologic and endocrine evidence lymphocytic involvement of the pituitary stalk and infundibulum was suspected. INTERVENTION: A diagnostic pterional craniotomy was performed. The diagnosis of lymphocytic infundibulohypophysitis was confirmed by biopsy. CONCLUSION: We present a case of lymphocytic infundibulohypophysitis. In view of its autoimmune pathophysiology the occurrence of this disorder in the postpartum period is not surprising, even though it has not been reported before. This rare disorder should be distinguished from the more common lymphocytic adenohypophysitis.