Objective Nephrotic syndrome (NS) is a kind of renal diseases characterized mainly by proteinuria and hypoalbuminemia. The disturbance of cellular immunity plays a major role in the pathogenesis of NS. The change of interleukin (IL) 13 produced by Th2 cells was investigated in 50 children with NS. Methods All the patients were selected during their nephrotic stage and remission stage. The expression of IL 13 protein and mRNA was determined by ELISA and reverse transcription polymerase chain reaction (RT PCR) respectively. Results ①The production of IL 13 in phytoheamagglutinin (PHA) stimulated mononuclear cells and the expression of IL 13 mRNA were significantly increased in patients in nephrotic stage as compared with controls. ②The expression of IL 13 protein and mRNA in patients in remission stage was similar to that in the normal controls. ③There was no correlation between IL 13 and laboratory parameters. Conclusion The results suggest that the disturbance of cellular immunity plays an important role in the pathogenesis of NS and they also demonstrate a protective role for IL 13 in the children with NS. Objectives: Objective Nephrotic syndrome (NS) is a kind of renal disease characterized mainly by proteinuria and hypoalbuminemia. The disturbance of cellular immunity plays a major role in the pathogenesis of NS. The change of interleukin (IL) 13 produced by Th2 cells was investigated in 50 children with NS. Methods All the patients were selected during their nephrotic stage and remission stage. The expression of IL 13 protein and mRNA was determined by ELISA and reverse transcription polymerase chain reaction (RT PCR) respectively. Results ① The production of IL 13 in phytoheamagglutinin (PHA) stimulated mononuclear cells and the expression of IL 13 mRNA were significantly increased in patients in nephrotic stage as compared with controls. ② The expression of IL 13 protein and mRNA in patients in remission stage was similar to that in the normal controls. ③There was no correlation between IL 13 and laboratory parameters. Conclusion The results suggest that the disturbance of cel lular immunity plays an important role in the pathogenesis of NS and they also demonstrate a protective role for IL 13 in the children with NS.