Twenty-two women with galactorrhea and/or amenorrhea were evaluated. Thyroxine (T4), thyroid-stimulating hormone (TSH), and visual fields were normal. Hyperprolactinemia (22 to 440 ng/ml) was present in 19 patients. Evidence of tumor was found in 73.7% of the woemn, whereas 26.3% were classified as functional. Three patients with empty sella syndrome showed normal prolactin levels (12.2 to 18.5 ng/ml). There was a significant negative correlation between prolactin levels and follicle-stimulating hormone (FSH) (P less than 0.05), but not between prolactin and luteinizing hormone (LH) levels. Hypocyloidal polytomography was better than plain x-ray films in detecting early prolactin-secreting pituitary tumors (14 patients). Pituitary testing using an insulin tolerance test showed a statistically significant difference in human growth hormone (hGH) reserve between tumor and functional groups (P less than 0.0005), and none for the cortisol response. The 17-hydroxycorticoid response to metyrapone was impaired in the tumor patients (group 1). Serum prolactin levels showed various degrees of suppression with L-dopa (9.3 to 98.8%), with no significant difference between the various groups.