In a surgical series of 755 pituitary adenomas, 51 cases (6.75%) showed intratumoral calcifications on microscopic examination and 13 of these were visible on roentgenographic examination (1.72%). Thirty-eight of these 51 cases were prolactinomas, the highest incidence being in male patients. There was no correlation between age, sex, levels of hormone, size of the tumor, and the presence of calcifications. Four patterns of radiological calcifications were encountered. Histologically, the calcifications were most frequently found within the tumor masses. Their rare occurrence within fibrous or degenerative areas speaks against their dystrophic nature. Previously reported calcified bodies in fetal and newborn pituitaries and the recently described physiological hyperprolactinemia in early infancy suggest a possible hormonal influence in the genesis of calcifications in prolactinomas.