Objective To investigate the expression of extracellular matrix metalloproteinase induced (EMMPRIN) in the synovial membrane of patients with rheumatoid arthritis (RA).Methods Immunohistochemistry were performed to characterize the EMMPRIN-expressing cells at sites of joint destruction derived from RA and osteoarthritis (OA) patients.Reverse trancription polymerase chain reaction (RT-PCR) was performed to study the existence of EMMPRIN in synovial membrane samples.And it was followed by computer assisted image analysis in order to detect the A values of their experession.Results EMMPRIN immunoreactivity was more intense in RA than in OA synovial membrane (P