The precise cause of rheumatoid arthritis (RA) is, as yet, unknown. But with more sophisticated techniques in the fields of immunogenetics and molecular biology, there is increasing knowledge of the pathophysiology of the rheumatoid joint. Pathophysiologic knowledge should be part of the orthopaedic nurse's repertoire when dealing with the “whole” patient; therefore orthopaedic nurses who care for patients with rheumatoid disease should understand certain pathophysiologic concepts. This article reviews the pathophysiology of the rheumatoid joint and describes the changes that take place in the joint with specific reference to the cells of the immune system, the synovium, and articular cartilage.