Diffuse idiopathic skeletal hyperostosis (DISH) is a common disorder of unknown etiology that is characterized by back pain and spinal stiffness. There may be mild pain if ankylosis has occurred. The condition is recognized radiographically by the presence of "flowing" ossification along the anterolateral margins of at least four contiguous vertebrae and the absence of changes of spondyloarthropathy or degenerative spondylosis. Even in patients who present with either lumbar or cervical complaints, radiographic findings are almost universally seen on the right side of the thoracic spine. Thus, radiographic examination of this area is critical when attempting to establish a diagnosis of DISH. The potential sequelae of hyperostosis in the cervical and lumbar spine include lumbar stenosis, dysphagia, cervical myelopathy, and dense spinal cord injury resulting from even minor trauma. There may be a delay in diagnosis of spinal fractures in a patient with DISH because the patient often has a baseline level of spinal pain and because the injury may be relatively trivial. The incidence of delayed neurologic injury due to such fractures is high as a result of unrecognized instability and subsequent deterioration. Extraspinal manifestations are also numerous and include an increased risk of heterotopic ossification after total hip arthroplasty. Prophylaxis to prevent heterotopic ossification may be indicated for these patients.