We retrospectively analyzed CT scans of 21 cavernous sinus lesions in an attempt to find the CT findings helpful to the differential diagnosis. With the integration of various CT findings it was possible to categorize the lesions into inflammatory, vascular, benign neoplastic and malignant metastatic lesions with few exceptions. Four of 5 cases of septic cavernous sinus thrombophlebitis revealed unilateral or bilateral multiple irregular filling defects in the enhancing cavernous sinus with or without orbital inflammatory change . Four of 5 cases of carotid-cavernous fistula demonstrated unilateral or bilateral diffuse bulging and homogeneous enhancement of cavernous sinus with obliteration of normal low densities of cranial verves and gasserian ganglion. Dilatation and tortuosity of superior ophthalmic vein were also associated. Four of 5 cases of benign neoplastic lesion showed well-circumscribed enhancing mass confined to cavernous sinus with pressure erosion or hyperostosis of adjacent bone. Five of 6 cases of malignant metastatic lesion showed various findings suggesting malignant nature such as destruction of adjacent bone or associated manifestation of intracranial spread. As compared with axial scan, coronal scan proved to be more sensitive in detection of subtle cavernous sinus expansion, and superior in evaluation of intracavernous neural structures, relationships with pituitary gland and osseous change of skull base. Axial scan, however, was superior in detection of associated orbital and intracranial abnormalities. Scans in both projections are needed in the evaluation of most cavernous sinus diseases.