Intervertebral bony bridging and enthesopathy can occur in both diffuse idiopathic skeletal hyperostosis (DISH) and ankylosing spondylitis (AS) and we have seen difficulties in the radiological differentiation between them. We describe 6 patients selected because the bridges resembled syndesmophytes and this initially suggested a diagnosis of AS, although other considerations showed them to be part of the radiologic picture of DISH. The previously reported suggestions of the coexistence of DISH and AS are reviewed.