With the use of axial and coronal computed tomography (CT), the authors compared the density, contrast enhancement, and dimensions of normal pituitary glands and pituitary microadenomas. The normal gland appears homogeneous, nearly isodense with brain tissue, and it enhances uniformly. Its upper surface is concave downward or flat and its height 2-7 mm. The cavernous sinuses, the third, fourth, and sixth cranial nerves, the infundibulum, and the adjacent carotid arteries are well demonstrated by CT. Abnormal height and upward convexity of the gland are reliable signs of prolactinoma; abnormal density and enhancement are suggestive signs. CT findings in prolactin- and ACTH-secreting tumors may differ. CT is more sensitive and more specific than polytomography in the diagnosis of pituitary adenoma.