Seventeen hyperprolactinemic patients aged from 24 to 58 years, with suspected pituitary adenoma, were studied. For diagnostic purposes, NOM and DOM tests were carried out, and also hypocycloidal tomography of the sella. In all cases in which the DOM test suggested the existence of a prolactinoma, the NOM test gave results in agreement with the former, except in one case. Hypocloidal tomography, although confirming the possibility of false negative (2 cases out of 17) or false positive results (1 case out of 17), demonstrated its diagnostic validity, although it was less sensitive than the biological tests.