Rheumatoid arthritis is a chronic systemic disease of unknown etiology characterized primarily by inflammatory synovitis. Its main features are aggressive joint inflammation that symmetrically affects multiple small joints of the hands and feet. It often accompanies involvement of extra-articular organs and a positive rheumatoid factor in serum. It can ultimately lead to joint deformity and loss of function. The onset of the disease may be related to genetic, infectious, and hormonal factors.