A case of lymphocytic infundibulo-neurohypophysitis (LINH) or 'stalkitis' in a 32-year-old woman who presented with diabetes insipidus (DI) during pregnancy is reported here. The diagnosis was made with MR imaging. The clinical and radiological features of this rare disorder and the differential diagnosis of infundibular mass lesions are discussed. The differentiation from lymphocytic adenohypophysitis (LAH) is made. No improvement of the DI accompanying LINH is achieved with trans-sphenoidal surgery. Hence, recognition of typical cases with MR imaging and appropriate medical management avoids unnecessary neurosurgery. This is the second reported case of LINH associated with pregnancy and may suggest an association.