To observe the binding activity of beta-2-glycoprotein I(beta(2)GPI) to hepatitis B surface antigen (HBsAg) and the possible roles of beta(2)GPI in hepatitis B virus (HBV) infection.The rationale of ELISA methods and ELISA-based research method and ligand-blotting technique were used to detect the specific interaction of beta(2)GPI with HBsAg.With the increase of rHBsAg, the binding of beta(2)GPI to rHBsAg elevated, and these changes had statistic significance. When we added non- biotinlyated beta(2)GPI, the OD value significantly decreased though they still were positively relevant to rHBsAg, suggesting non- biotinlyated beta(2)GPI competed with biotinlyated beta(2)GPI to saturate the binding sites on rHBsAg. Meanwhile BSA was used as negative control to substitute for rHBsAg coating the plates. The results indicated no interaction between beta(2)GPI and BSA, suggesting the affinity of beta(2)GPI to rHBsAg was specific. The ligand blotling indicated that beta(2)GPI might bind to rHBsAg no matter whether it was under reduced condition or not.The binding of beta(2)GPI to HBsAg suggests that beta(2)GPI may be a carrier of HBV and that beta(2)GPI may play important roles in HBV infection.