PIP: Prolactin is a polypetide hormone structurally similar to a growth hormone. It is secreted by lactotrophs in the anterior pituitary gland. The levels rise during pregnancy in response to estrogens formed by the feto-placental unit. Hyperprolactaemia in women causes a characteristic pattern of reproductive disturbance. The most severe form accounts for 15-20% of amennorhoea. Subnormal secretion of estradiol occurs because ovarian follicles do not mature. Symptoms are dyspareunia and dryness during intercourse. Hyperprolactinaemia in men suppresses gonadtropin secretion, and testosterone concentrations may be subnormal. Suppression of prolactin can be achieved by withdrawing drugs which provoke prolactin release, by correcting hypothyroidism and by direct treatment of a prolactin-secreting pituitary tumor. Bromocriptine suppresses prolactin secretion by direct action on the pituitary lactotrophs. It may be possible to avoid procedures such as radiation therapy and surgery in patients with small pituitary tumors who wish to become pregnant, but close cooperation of patients in special units is essential.