Thirty-eight patients with surgically or biochemically confirmed pituitary adenomas were examined on a 1.5 T MRI system by means of spin echo technique with 3 mm slice thickness. T1 weighted sagittal and coronal sections were obtained before and after the administration of Gd-DTPA. Compared with the normal pituitary anterior lobe, 8% of the adenomas were hyperintense, 45% were isointense, 42% were hypointense and 5% were inhomogeneously intense. After Gd-DTPA administration, 13% enhanced to a greater degree, 10% to the same, and 57% to a lesser degree than the normal pituitary tissue. Twenty percent showed inhomogeneous enhancement. In 10%, there was evidence of adenoma only in the enhanced images. The delineation of the adenoma from the cavernous sinus was improved from 47% in unenhanced scans to 91% after Gd-DTPA administration.