In the present study, we examined the expression of 10 different ADAM species with a putative metalloproteinase motif in synovial tissues of RA and osteoarthritis (OA), correlation of ADAM15 expression with synovial pathology, localization of ADAM15 in RA synovium, and the mechanism of regulation of ADAM15 expression in RA synovial fibroblasts and endothelial cells. Here, ADAM15 is linked to rheumatoid arthritis.