In a 76-year-old woman with hyperthyroidism, hyperprolactinemia and thickening of the pituitary stalk on magnetic resonance imaging (MRI) was presented. Thyroid stimulating antibody (TSAb) was positive and antipituitary antibodies against 49 and 68 kD human anterior pituitary membrane antigens were detected immunologically. Secretion of pituitary hormones was almost normal except for suppressed TSH and hyperprolactinemia. As autoimmune etiologies were likely involved in the disorders, autoimmune hypophysitis associated with Graves’ disease was arrived at as the plausible diagnosis.