Abstract： Objective To investigate the altered expression of mRNA and protein of IL- 17 of peripheral blood in children with allergic asthma.Methods Thirty cases with allergic asthma of occurrence perod in the First Affiliated Hospital of Guangzhou University of Traditional Chinese Medicine and 25 cases with asthma of remission period were enrolled in the study.Thirty healthy children were used as control.Their mRNA levels of IL-17 in peripheral blood were detected by real-time quantitative PCR and the protein level by ELISA.Results In asthma patients of occurrence period,the expression of IL- 17 mRNA was significantly elevated and higher than that in patients of remission period and healthy children [ (10.20± 3.32)％ vs (8.61± 1.62)％ and (3.84± 1.36)％,all P＜0.05 ].Moreover,the expression of IL- 17 protein in patients with asthma of occurrence period was higher than that in patients of remission period and healthy children as well (P＜0.05).Conclusion In occurrence period,the significantiy elevated expression of IL- 17 is found in the peripheral blood in children with allergic asthma,which indicates that IL- 17 may play an important role in the occurrence progression of allergic asthma.