The relationship between glutaraldehyde-treated polymeryzed human serum albumin (pHSA) and HBe antigen (HBeAg)-positive serum was examined by the use of a new enzyme-linked immunosorbent assay (ELISA). The author succeeded in measuring the pHSA binding activity (pHSA-BA) of HB surface antigen (HBsAg) particles in the present ELISA method using horseradish peroxidase-labelled pHSA after fixation of HBsAg on an anti-HBs-coated well of polystyrene microplates. In HBeAg-positive group, the pHSA-BA of sera of 40 asymptomatic carriers and 2 chronic persistent hepatitis (CPH) patients were higher than those of 8 chronic active hepatitis (CAH) (p less than 0.01) and 8 liver cirrhosis sera (p less than 0.05). On the contrary, in the anti-HBe-positive group the pHSA-BA of 17 asymptomatic carriers and 3 CPH sera were lower than those of 8 CAH (p less than 0.005) and 10 liver cirrhosis patient sera (p less than 0.005). In the both-negative group the pHSA-BA of 8 asymptomatic carrier and 3 CPH sera were also lower than that of 8 CAH (p less than 0.05). In acute exacerbation of HBsAg-positive CAH the pHSA-BA elevated one to two months before the peak of S-GPT level, being correlated with the DNA-polymerase activity. Because of its apparent reproducibility, it is concluded that low cost and some advantages may have clinical utility in the same setting as the HBeAg is now used.