Thirty three hyperprolactinemic women, aged 16-46 years, have been investigated by pituitary CT and MRI scans, searching for a microadenoma. The MRI scan with Gadolinium injection (MRI G+) appeared more efficient than the CT scan to detect a picture highly suggestive of a microprolactinoma (30/33 positive scans vs 21/33, respectively, p = 0.06). However, when the CT scan was performed optimaly (i.e. thin cuts, sequential imaging after iode injection, no artefact), its diagnostic potenty was close to the one of MRI G+, missing only 17.6% of lesions. All these were less than 5 mm in diameter. The indirect signs of microadenoma (focal convexity of the superior surface of pituitary, tilting of pituitary stalk, focal sella floor erosion or destruction) had a minimal value. Their sensitivity was 66.6% and 63.3 for convexity, and 63.3 and 46.6% for tilting of pituitary stalk, by MRI and CT scans, respectively. Therefore, they did not afford any help in our experience. Considering the cost and the limited accessibility of MRI, at least in our country, we advise to use CT scan as the primary morphologic means to detect a microadenoma.