Background: The sternoclavicular joint (SCJ) is the only synovial articulation between the upper extremity and the trunk. This joint is one of the most frequently used joints, so osteoarthritis (OA) should be very common. However, there are few studies about OA in this joint. Methods: In this study, 48 sternoclavicular joints from the left and right joints of 23 cases and two left joints from two further cases were studied. Right and left sternoclavicular joints were removed together in an unselected sequential autopsy series. Ninety two blocks were prepared by cutting every SCJ to superior and inferior parts. Using histological staining, the articular surfaces of the SCJs were assessed microscopically. Contact radiography was done to help assessing the presence or absence of osteoarthritis. Results: The features of normal joints were found in 18 blocks. Osteoarthritis changes were seen in 82 of the 92 blocks. There was no significant correlation between age and osteoarthritis. No differences in the degenerative changes were found between the sexes. Severe osteoarthritis changes were more common in the right SCJ and inferior part of the joint than in the left and superior parts respectively. The osteoarthritis changes were severe in 36.6% of cases and mild to moderate in 48.8%. Conclusion: OA was very common in these SCJs, which is not related to age and sex of the cases. There are clear changes in structure and glycan expression in the articular cartilage of the osteoarthritic sternoclavicular joint, which allow a distinction to be made between mild, moderate, and severe osteoarthritis and normal cartilage. Histochemical staining of the joints can lead to accurate diagnosis of this disease.