Аннотация:Abstract The intraperitoneal injection of an aqueous suspension of cell wall fragments from group A streptococci induces a chronic intermittent arthritis in rats that is associated with the persistence of cell wall material in joint tissues. The radiographic techniques utilized to study this experimental model are described and the radiologic findings encountered during the natural history of the disease are presented. The progressive erosive synovitis of this model is similar to that seen in rheumatoid arthritis.