We analized computed tomography (CT) of 29 cases of various orbital diseases in pediatric age group. Diagnoses were confirmed by either operation or direct ophthalmoscopy. The patients were examined during the period of last 3 years. The results were as follows: 1. Of 29 cases, 21 were male and 8 were female, and the age ranged from 20 days to 15 years. 2. Intraorbital tumors were 13 cases consisting of 7 retinoblastoma, 3 pseudotumor, and 1 each of congenital teratoma, cavernous lymphangioma, and optic glioma. Of remaining 16 cases. 6 had orbital fracture. 5 persistent hyperplastic primary vitreous (PHPV), 3 vitreous opacity, and 2 primary glaucoma. 3. The CT findings of the retionblastoma were a lobulated or oval soft tissue mass density (40-60 HU) extending into the vitreous without significant enhancement on postcontrast scan. Of 7 cases, 4 had calcifications within the tumors. The extraglobal extension of the tumor was shown in 2 patinets demonstrating markedly thickened clera with enhancement and dilated optic nerve. 4. There were 5 patients with PHPV having a history of white pupil since birth, and all were affected unilateraly. Four patients had vitreous opacity and 3 of those showed either linear or branching tree-like densities within the vitreous on the postcontrast scan. Another one had a lobulated increased density protruding into the vitreous which was difficult to differenciate from the similar finding of retinoblastoma. Remaining one case demonstrated a deformed and decreased density in the lesional lens without change in the density of the vitreous. This was confirmed to be caused by persistence of the embryonic hyaloid artery attached to the posterior capsule of the lens. 5. There were 3 patients with vitreous opacity and 2 of them were dut to retinal detachment and 1 was caused by retrolental fibroplasia. The CT findings of retinal detachement were homogeneous or heterogenous opacities in the vitreous. In a case of retrolental fibroplas a, irregular, band-like density was seen along the posterior wall of the globe bilaterally. 6. Two cases of primary glaucoma showed large globe with a widened anterior chamber. 7. Among 6 cases of orbital fractures, 5 were blow-out fracture. The blow-out fractures showed fractures of the medial orbital wall or orbital floor with herniated intraorbital contents into the neighboring ethmoid or maxillary sinus.