We describe a new method of stabilising a painful unstable sternoclavicular joint using the sternocleidomastoid tendon and passing it through the medial clavicle and onto the manubrium sternum. This method is simple, reproducible and avoids the potential risks of reefing the joint to the first rib. The technique was used in seven cases of sternoclavicular joint instability in six patients who were reviewed at a mean of 39.7 months (15 to 63). Instability was markedly reduced or eliminated in all cases, but in one there was occasional persistant subluxation. There were minor scar complications after two procedures and one patient had transient ulnar neuritis. This procedure provides satisfactory results in the medium term.