METHODS A case report of a spinal subarachnoid hematoma (SSAH) associated with hyperextension fractures complicating diffuse idiopathic skeletal hyperostosis (DISH). OBJECTIVE To report the first case of a SSAH complicating spinal fracture in DISH. BACKGROUND A SSAH is very rare condition. And there had been several reports on spinal fractures in DISH through fused spinal segments, but no report related with SSAH associated with spinal fracture in DISH patient. METHODS A 78-year-old female patient was admitted for pain in the back and lower limbs and paraparesis after being fall on her back. On simple radiographs, DISH with anterior cortical bone deficit and increased height were presented at the level of L1. MR and Myelography computed tomography images revealed an extension type of fracture with an irregular shaped subarachnoid hematoma within the dura. Differential diagnosis from infection or tumorous condition was required. RESULTS Durotomy and 1 to 2 laminectomy was performed to improve neurologic symptoms. The posterior yellow ligament was seen partially ossified and adhered to dura without dura tear. The hematoma was found adherent to the nerve roots of the cauda equina and pia mater. After posterior segmental screw instrumentation and fusion from T10 to L3, anterior interbody fusion was performed with extrapleural approach after dissected the 11th rib, using L1 corpectomy and titanium mesh cages. There was no evidence of infection or tumor. After surgery, motor and sensory function of the lower limbs improved remarkably with solid bony union. CONCLUSIONS The first case of a SSAH complicating spinal fracture in DISH is presented. The patient was successfully treated with a staged operation including posterior decompression with fusion and anterior interbody fusion.