The sternomanubrial joint (SMJ) was evaluated on the lateral chest radiograph in 177 patients with rheumatic disease and 69 non-rheumatic controls. Abnormalities were categorized as inflammatory changes, proliferative changes, or bone fusion. Patients with rheumatoid arthritis, psoriatic arthritis, or gout were found to have an increased incidence of inflammatory changes. Rheumatoid variants predisposed to early fusion of the SMJ. Patients with diffuse idiopathic skeletal hyperostosis (DISH) exhibited massive and unique hyperostotic changes.