Objective To observe the expression of Th1/Th2 cytokines in children with Wilms' tumors.Methods The gene expression of Th1/Th2 cytokines in children with Wilms' tumors was detected by RT-PCR.Results The expression of Th2 cytokines was dominant in the peripheral blood and tumor cells.Conclusion The dominant expressions of Th2 cytokines in children with Wilms' tumor may be related to the development and progression of Wilms' tumors.