PURPOSE: In accordance with the increasing number of accidents caused by various reasons and recently developed fine diagnostic skills, the incidence of orbital blow-out fracture cases is increasing. As it causes complications, such as diplopia and enophthalmos, surgical reduction is commonly required. This article reports a retrospective series of 5 blow-out fracture cases that had unusual nerve injuries after reduction operations. We represents the clinical experiences about treatment process and follow-up. METHODS: From January 2000 to August 2009, we treated total 705 blow-out fracture patients. Among them, there were 5 patients(0.71%) who suffered from postoperative neurologic complications. In all patients, the surgery was performed with open reduction with insertion of Medpor(R). Clinical symptoms and signs were a little different from each other. RESULTS: In case 1, the diagnosis was oculomotor nerve palsy. The diagnosis of the case 2 was superior orbital fissure syndrome, case 3 was abducens nerve palsy, and case 4 was idiopathic supraorbital nerve injury. The last case 5 was diagnosed as optic neuropathy. Most of the causes were extended fracture, especially accompanied with medial and inferomedial orbital blow-out fracture. Extensive dissection and eyeball swelling, and over-retraction by assistants were also one of the causes. Immediately, we performed reexploration procedure to remove hematomas, decompress and check the incarceration. After that, we checked VEP(visual evoked potential), visual field test, electromyogram. With ophthalmologic test and follow-up CT, we can rule out the orbital apex syndrome. We gave Salon(R)(methylprednisolone, Hanlim pharmaceuticals) 500 mg twice a day for 3 days and let them bed rest. After that, we were tapering the high dose steroid with Methylon(R)(methylprednisolon 4 mg, Kunwha pharmaceuticals) 20 mg three times a day. Usually, it takes 1.2 months to recover from the nerve injury. CONCLUSION: According to the extent of nerve injury after the surgery of orbital blow-out fracture, the clinical symptoms were different. The most important point is to decide quickly whether the optic nerve injury occurred or not. Therefore, it is necess is to diagnose the nerve injury immediately, perform reexploration for decompression and use corticosteroid adequately. In other words, the early diagnosis and treatment is most important.