Two patients with amenorrhea-galactorrhea and Cushing's disease due to pituitary tumor are presented. In both cases, a diagnosis of prolactin-secreting tumor with moderate hyperprolactinemia was established, then Cushing's disease developed years later. Despite the typical clinical features of Cushing's disease, a dexamethasone suppression test inhibited both blood ACTH and cortisol concentrations in the 2 patients. Hypophysectomy was performed in 1 case, and the histologic study revealed the presence of a cromophobe adenoma. The other case was treated by external radiation which improved the clinical situation. Clinical and endocrinological studies in these 2 cases were compared with previous reports in the literature in order to discuss the etiology of this unusual association. It is concluded that patients with pituitary tumors presenting moderate hyperprolactinemia may also have excessive secretion of ACTH.