To evaluate characteristic CT findings of orbital pseudotumor and to define differential points from other pathology, the authors retrospectively reviewed CT of 19 patients who were prooen to have orbital pseudotumor by clinical course and, in some cases, biopsy. A variety of CT findings including extraocular muscle thickening (11 cases), streaky infiltration of retroorbital fat (11 cases), mass formation (10 cases), optic nerve thickening (6 cases), conjunctival thickening (5 cases), scleral thickening (4 cases), enlarged lacrimal gland (4 cases) and destruction of orbital bone (2 cases) were observed. Thickening of the anterior portion and irregular margin were characteristic findings of extraocular muscle and optic nerve lesions. Mass formation predominantly occurs in the anterior portion of the orbit. In most cases more than two orbital structures are involved by lesion.