Rheumatoid arthritis (RA) is a chronic autoinflammatory disorder that affects small joints. Despite intense efforts, there isno definitive marker yet for early diagnosis RA and for monitoring the progression of this disease. We sought to catalog the proteins present in the synovial fluid of patients with rheumatoid arthritis. To identify lower abundance proteins, we undertook two approaches – we depleted the abundant proteins using a multiple affinity removal system (MARS14) column and we enriched glycoproteins using a lectin affinity column. The peptides were analyzed by LC-MS/MS on a high resolution Fourier transform mass spectrometer.