Twenty-nine patients with orbital inflammatory disease(OIDs) were retrospectively reviewed in order to analyze detailed CT finding which might aid in differenciating OIDs. This study comprised 18 pseudotumors, 5 thyroid ophthalmopathies, and, in addition, we found bone erosions involving the orbital apices in 2 cases. Bone lisions of the pseudo tumors, which have been rarely reported, were present in 7 cases in our series. Bilateral exophthalmos, myositis, and retrobulbar fat deposition were readily detected by CT in thyroid ophthalmopathy, and, in addition, we found bone erosions involving the orbital apices in 2 cases. In orbital cellulitis, extraorbital soft tissue swelling and lateral displacement of the medial rectus muscle in cases with ethmoiditis were the most conspicuous features. In summary, because of the overlapping CT findings in OLDs, cardful examination of CT findings regarding the mode of EOM involvment and the presence or absence of scleritis or sinusitis might help narrow down the differential diagnosis. A pseudotumor with bone lesions could be mistaken as a malignant lesion, and therefore it is necessary to correlate clinical features with CT findings for an accurate diagnosis.