目的　探讨儿童反复呼吸道感染 (RRTI)的病因。方法　采用径向免疫扩散法检测血清免疫球蛋白 (Ig)G亚类、IgA亚类和T细胞亚群的变化。选择RRTI患儿 42例与同年龄的健康儿童以配对方式进行对照观察。结果　RRTI组检出IgG亚类缺陷 2 0例 ,占 47.6 2 % ,以IgG2 和IgG4 缺陷为主 ;IgA亚类缺陷 17例 ,占40 .47% ,以IgA1缺陷为主 ;CD+ 3 、CD+ 4细胞及CD+ 4/CD+ 8显著低于对照组 ,P均 <0 .0 0 1。结论　IgG、IgA亚类缺陷是儿童RRTI的主要原因之一 Objective To investigate the etiology of RRTI in children. Methods The changes of immunoglobulin (Ig) G subclasses, IgA subclasses and T lymphocyte subsets were detected by radial immunodiffusion. Forty-two children with RRTI and healthy children of the same age were enrolled in the study. Results 20 cases of IgG subtype defects were detected in RRTI group, accounting for 47.6%. The majority of IgG2 and IgG4 were found in the RRTI group. IgA subtype defects were found in 17 cases (40.47%) with IgA1 deficiency. CD + 3 and CD + 4 Cells and CD + 4 / CD + 8 were significantly lower than the control group, P <0.01. Conclusion The subclinical IgG and IgA defects are one of the main causes of RRTI in children