For this reason, the main objective of this study was to determine the usefulness of the evaluation of particular types of plasma sulfated glycosaminoglycans (i.e., CS/DS and HS/H)—products of tissue proteoglycan degradation—as new biomarkers for monitoring the effectiveness of TNF-α inhibitors (TNFαI) in the treatment of RA. The gene discussed is TNF; the disease is rheumatoid arthritis.