Rheumatoid Arthritis (RA) is a chronic and progressive autoimmune disease that affects joints symmetrically. Its etiology is unknown; however, genetic sensitivity as a risk factor has been proposed in addition to the postulated infl uence of an unspecifi c agent that provokes excessive production of cytokines that cause alterations in cell regulation. RA is the most frequent disease among infl ammatory arthropathies. It has a prevalence of approximately 1% worldwide; meanwhile its incidence has been reported as up to three times higher in women than in men. An important symptom in RA is the infl ammation of synovial membrane with hyperplasia; a membrane richly represented with lymphocytes B, lymphocytes T, and macrophages.