Forestier disease, or ankylosing hyperostosis, is a common disorder of middle-aged and elderly persons. Characteristic clinical and radiographic features enable the physician to distinguish between this disease and ankylosing spondylitis. The principal clinical features include aching spinal stiffness with relative preservation of function and minimal evidence of spinal immobility. Many patients have elbow and heel pain and dysphagia. Typical radiographic findings are ligament ossification, para-articular osteophytosis, and bone production at sites of tendon and ligment attachment in spinal and extraspinal locations. The extraspinal roentgenographic manifestations are so characteristic that when present, they allow the diagnosis of spinal ankylosing hyperostosis to be suggested, even in the absence of axial radiographs.