PURPOSE: To evaluate the usefulness and radiologic findings of CT in the diagnosis of orbital blow-outfracture. MATERIALS AND METHODS: Forty-four patients with orbital blow-out fractures diagnosed by clinicalfindings and CT were evaluated retrospectively. On CT images, we evaluated the site and frequency of fracture,herniation of orbital fat, extraocular muscle abnormality, intraorbital hematoma, and intrasinus hemorrhage. RESULTS: Forty-eight sites of orbital wall fractures were seen. Of these, 25(52.1%) were observed at the medialwall and 18(37.5%) at the inferior wall. Combined fracture of the medial and inferior wall was seen in fivecases(10.4%), and orbital fat herniation to adjacent sinuses in 25. Associated extraocular muscle abnormalitieswere seen at the medial rectus (n=20) and inferior rectus muscle(n=18). Intrasinus hemorrhage was seen in 15cases, and intraorbital hematoma in five. CONCLUSION: CT is a useful diagnostic modality for the evaluation oforbital blow-out fracture and associated soft tissue abnormalities.