A 29 year old woman came to the hospital due to headache, facial edema, amenorrhea and galactorrhea. On the lahoratory studies, not only hyperprolactinemia and pituitary enlargement, but also primary hypothyroidism were found. Symptomatic and radiological resolution could be achieved by the thyroid hormone replacement only. This case emphasizes the need for evaluation of thyroid status in patients vith presumptive prolacin producing pituitary tumors before initiation of the therapy for hyperprolactinemia