Diffuse idiopathic skeletal hyperostosis (Forestier's disease, DISH, or ankylosing hyperostosis), is a well-described disorder of middle-aged and elderly people. DISH has a unique spinal pathology, as well as characteristic extraspinal manifestations. Ankylosing spondylitis, a relatively common disease usually affecting younger people, also has spinal and extraspinal abnormalities, but it has ... [Show full abstract] pathologic and radiographic pictures distinct from DISH. Resnick stated that DISH and ankylosing spondylitis may occur concomitantly in a given elderly patient, but we have found no published case reports. We report here a 72-year-old man whose radiographs of his cervical spine revealed changes of DISH while those of his lumbar spine showed changes of ankylosing spondylitis. To our knowledge, this is the first case report in the literature illustrating the coexistence of these 2 diseases.