Objective: To determine the antibody titer in the serum of allergic rabbits after the injection of 1, 3-di-caffeoylquinic acid contained in Shuanghuanglian injection.Methods: The complete antigen was prepared by incubating the suspected small molecular hapten 1, 3-di-caffeoylquinic acid contained in Shuanghuanglian injection with the serum from the normal rabbits.The specific antibody was obtained in the immunized rabbits.The antibody titers of antiserum were measured by ELISA kits.Indirect competitive ELISA was used to determine serological specificity, and the obtained data was used to plot the inhibition curves.The content of IgE antibody in the antiserum of rabbits was detected by rabbit immunoglobulin E (IgE) ELISA kits.Results: The antibody titer (A) of 1,3-di-caffeoylquinic acid was 2 times higher than that of the negative control, which indicated its potential allergenicity.The regression equation was I=0.170 6 lg C + 0.317 5 , which was with the correlation coefficient of r=0.985 4 , the detection limit of IC 10 =57.40 μg·ml-1 and the half inhibitory concentration of IC 50 =8.732 0 mg·ml-1.Furthermore, the exogenous IgE antibody was produced in the rabbits.Conclusion: The results indicated that the hapten substance 1,3-di-caffeoylquinic acid in Shuanghuanglian injection was allergenic under the present experimental conditions.