Objective:To study the significance and application of serum eosinophil cationic protein(ECP) and IgG4 antibody in patients with allergic rhinitis treated by allergic specific immunotherapy.Method:The level of IgG4 antibody and eosinophil cationic protein in serum was measured in 33 cases of allergic rhinitis before treatment and half a year and one year after treatment.The change of ECP level was observed in different age groups,and the relationship between serum IgG4 and ECP after treatment was analyzed.Result:IgG4 antibody in the serum significantly increased after treatment,and the difference was statistically significant(P<0.05).In the serum ECP content gradually reduced after treatment,and the difference was statistically significant(P<0.05).No obvious difference in ECP level was observed among dfferent age groups after treatment (P<0.05).The level of serum IgG4 was negatively correlated with serum ECP level despite statistical insignificance(r=-0.138,P>0.05).Conclusion:ECP is a sign of eosinophil activation,which is an important factor leading to the nasal inflammation.The content of serum ECP can be used as an indicator for patients with allergic rhinitis recieving nonspecific immune treatment .IgG4 antibody is a relatively reliable indicator to evaluate the treatment effect of specific immunotherapy,and may be negatively related to the serum ECP levels.