A case of spontaneous atraumatic subluxation of the sternoclavicular joint was reported. The patient, a 27-year-old female, complained of pain, click and the bony prominence in her right sternoclavicular joint when raising her right upper extremity. The X-ray, CT and 3D-CT showed subluxation of the right sternoclavicular joint, and arthrography showed pooling of the contrast medium. The joint was stabilized surgically using the fascia lata and the subclavius muscle. The post operative course was satisfactory, without further subluxation and pain. Spontaneous atraumatic subluxation of the sternoclavicular joint is a rare disease. The sternoclavicular joint has an unstable bony structure and it's stability depends on the ligaments (costoclavicular, sternoclavicular and interclavicular ligaments) and capsule. lt is believed that the subluxation occurred due to weakness in these supporting tissues.
