Collagen is the major structural protein in the human body, especially in connective tissues. There are more than 13 types of collagen. Among them, type II collagen is a main component of articular cartilage structure. Altered immunological conditions against type II collagen may be closely related to the pathologic conditions of joint, especially arthritis. Since 1977, animal model for collageninduced arthritis(CIA) has been developed and used in the investigation of arthritis. In those animals, high titers of anti-type II collagen antibody were noticed. Pathologic findings were similar to rheumatoid arthritis of human, which suggested that rheumatoid arthritis might be one of the autoimmune diseases. There had been many reports about elevation of serum and synovial level of anti-type II collagen antibody in rheumatoid arthritis patients. But majority of them did not discriminate the antibody titers according to the type of immunoglobulin(i.e. IgG, IgM). And the question whether the elevated antibody titers are cause or effect of the arthritis is still in controversy. In this study, the serum levels of anti-type II collagen antibody were determined in 82 persons(35 degenerative arthritis patients, 24 rheumatoid arthritis patients and 22 normal controls without any joint problem) via ELISA method. In each person the serum IgG, IgM and IgG+M+A antibody levels against bovine type IIcollagen and chicken typeII collagen were determined individually. Statistical evaluation of these data among degenerative arthritis group, rheumatoid arthritis group and normal control group was performed. The results were as follows; 1. Degenerative arthritis group revealed significant elevation of anti-type II collagen antibody(IgG, IgG+M+A) compared to normal control(p<0.05). 2. Rheumatoid arthritis group showed significant elvation of IgM and IgG+M+A compared to normal control. 3. Between degenerative arthritis and rheumatoid arthritis group, no sigificant difference was noticed. 4. Rheumatoid arthritis group showed significant increase of IgM antibody level compared to normal control. 5. Female rheumatoid arthritis group showed significant increase of IgM level compared to female degenerative arthritis group. These findings suggested that the elevation of anti-type II collagen antibody titer is not specific for rheumatoid arthritis and related with general pathologies destroying articular cartilage. And it is suggested that anti-type II collagen antibody associated with rheumatoid arthritis is mainly IgM proportion, especially in female patients. So further investigation of anti-type II collagen antibody associated with rheumatoid arthritis is needed to target IgM antibody.