In evaluating over 300 patients with sellar and parasellar lesions, the computed tomographic (CT) appearance of the cavernous sinus was studied. Optimal visualization of the cavernous sinus was obtained with continuous contrast enhancement of both axial and coronal tomograms. The coronal projection and reformatted views provided imaging of the cranial nerves within the cavernous sinus. In addition to the physiologic CT appearance of the cavernous sinus, a variety of pathologic conditions are illustrated. CT criteria suggesting an abnormal cavernous sinus are: (1) asymmetry of size; (2) asymmetry of shape, particularly the lateral wall; and (3) focal areas of abnormal density within the sinus. © 1982, American Academy of Ophthalmology. All rights reserved.