The pathogenesis of rheumatoid arthritis centers on as yet unknown initiating events in the synovium that result in synovial vessel proliferation, and upregulation of endothelial cell ligands for leukocyte adhesion molecules. Ligation of adhesion molecules on synovial microenvironment cells and immune cells probably regulates synovial and immune cell inflammatory cytokine production. Interruption of adhesion molecule function and interruption of inflammatory cytokine production are promising new sites of therapeutic inhibition of synovial inflammation.