Abstract: Purpose: The pathogenesis of Rheumatoid Arthritis (RA) is not well understood. Looking for three mediators [Soluble Interleukine 2 Receptor (SIL2R), ß2 Microglobulin (ß2M) and Tumor Necrosis Factor α (TNF α)] in RA patients sera and synovial fluid (SF) may clear some aspects of it. Methods: The above named mediators were estimated in 72 RA patient sera and SF, 13 patient with osteoarthritis (as patient control) and 130 blood donor (as normal ...