[Objective] To identify the risk factors for delay in diagnosis of spinal fractures in patients with ankylosing spondylitis(AS) [method] Retrospective case series of patients with AS and spinal fracture admitted over a 9-year period at our hospital.[Result] Total of 7 patients experienced delay in diagnosis. Of the 7 patients, One patient died of missed occult cervical spine fracture and secondary spinal cord injury 10 days after the accident; 3 patients experienced multiple spinal fracture, and one of the fracture was overlooked; one patient presented 6 months after surgery for cervical spine fracture and spinal cord injury because of deformity of back and old fracture of thoracolumbar spine was found; 2 patients were not presented immediately after mild injury.[Conclusion] delay in diagnosis of spinal fracture in patients with AS often occurred in patients with multiple spinal fractures ; overlooked occult fracture and delay in presentation are also common reasons for delay in diagnosis.