In 1987, the ACR (American College of rheumatology) guidelines for classification of RA were published and the JCR (Japan College of rheumatology) classification of early diagnosis for RA was established in 1994. The determination of rheumatoid factor (RF) was included in both the above classification standards. However, Ig-M type of RF has problems in specificity and sensitivity. Recent progress in various RA studies has revealed the molecular mechanism of RA and new therapy and laboratory tests (ie. CA-RF, MMP-3) have been developed. Thus, determination changes in various diagnostic markers such as MMP-3, and inflammatory cytokines (ie. IL-1beta, IL-2, IL-6, IL-8, IL-18) are important for treatment of RA patients.