Hyperprolactinemia is common and mainly encountered in premenopausal women. The most prevalent causes are drugs (estrogens, neuroleptics), hypothalamic and pituitary disorders (functional abnormalities, intrasellar adenomas, suprasellar lesions) and hypothyroidism. Although the typical picture is the amenorrhea-galactorrhea syndrome, hyperprolactinemia may be revealed by many other features, including obesity, hirsutism and sterility. When plain roentgenograms show a normal sella, neither dynamic tests nor polytommography can lead to unequivocal diagnosis of a tumor. Computerized tomography scanning is now the most reliable investigation in patients with hyperprolactinemia resulting from an obvious or suspected tumor.