CT scanning demonstrated orbital tumors in 15 patients with progressive unilateral proptosis in whom the diagnosis was confirmed by surgery or biopsy. The CT scan was the only abnormal study in 13 patients. In two patients, standard roentgenogram studies and CT scan were both abnormal, but the CT scan was of greatest value in identifying the tumor. Orbital structures are clearly demonstrated when scans are performed at lower level than those used in standard cerebral studies. The large fat content of the orbit is of low density and appears dark on the cathoderay tube. The tumors were of higher densities and appeared as white homogenous or speckled masses against the dark background. Surgical findings confirmed the accuracy of CT scanning in determining the tumor size and location. A new 160X160 grid provides remarkable resolution of orbital structures such as the optic nerve and extraocular muscles. Moreover, it is now possible to visualize ten consecutive ventral to dorsal slices of orbital tissue providing greater detail of orbital pathology. CT scanning will probably be an indispensable tool in the diagnosis of orbital tumors.