Extracellular matrix proteins are increased in inflammatory synovitis. We showed previously that the in situ expression of the corresponding extracellular matrix receptors (beta 1-integrins) is enhanced in synoviocytes (SC) of synovitis of different etiology (16). To investigate the adhesion of SC to extracellular matrix proteins, we examined the attachment of SC from normal and inflamed synovia to fibronectin, tenascin, laminin and collagen type IV. Compared to normal SC and SC of osteoarthritis, SC of rheumatoid arthritis showed an increased binding to tenascin, laminin, fibronectin and collagen type IV, suggesting a distinctive interaction of SC and extracellular matrix proteins in rheumatoid arthritis. Furthermore, the increased binding of SC of rheumatoid arthritis to extracellular matrix proteins may play a role in tissue remodelling associated with rheumatoid arthritis.