In women with galactorrhea, amenorrhea/oligomenorrhea, hyperprolactinemia and radiographic evidence of a pituitary tumor, the presumed etiology is usually a primary prolactin-secreting tumor. We treated two patients whose presenting symptoms (galactorrhea and oligomenorrhea) and initial investigation (which showed radiographic enlargement of the sella and hyperprolactinemia) suggested a prolactin-secreting pituitary tumor. However, after further endocrinologic investigation, transsphenoidal exploration and ultrastructural-immunohistologic evaluation of the excised pituitary tumors, the tumors were found to be composed of cells characteristic of growth-hormone and adrenocorticotropic-hormone production. These data are consistent with the hypothesis that any factor or factors increasing intrasellar pressure, including pituitary tumors originating in cells other than galactotrophs, can elevate serum prolactin and present clinically as galactorrhea-amenorrhea. They suggest further that a diligent search be done for elevations of other pituitary trophic hormones when a pituitary tumor is suspected in order not to overlook other kinds of serious endocrinopathy.