Intra-articular sodium hyaluronate was used to treat 16 horses with osteo-arthrosis of the carpus, fetlock, hock and coffin joints. In 11of these horses lameness was completely relieved. In addition, 5 horses that underwent carpal surgery for the removal of chip fractures received sodium hyaluronate 10–14 days later. In thesecases, it appeared to have a beneficial effect, resulting in a greater range of movement of the carpus soon after surgery and less swelling of the joint capsule. The results of synovial fluid analysis in horses with osteo-arthrosis, and with carpal fractures, are also presented.