Abstract: Objective To investigate the differentiation direction of Th cells in peripheral blood of patients with chronic urticaria and to analyze its possible immunopathogenesis. Methods A four-color immunoflurescent antibody was used to stain the peripheral blood T cells in observation and control groups.The concentrations of CD⁴⁺/IFN-γ⁺（Th1） and CD⁴⁺/IL-⁴⁺（Th2） cells in peripheral blood of both groups were measured by flow cytometry.Peripheral blood mononuclear cells（PBMC） were separated from peripheral blood specimens from patients with chronic urticaria and controls.Reverse transcription-polymerase chain reaction（RT-PCR） was performed to analyze the expression of IFN-γR mRNA in PBMC. Results Compared to the controls,the number of Th1 cells and the ratio of Th1/Th2 were decreased while the number of Th2 cells was increased dramatically（P＜0.05） in patients with chronic urticaria（P＜0.05）.The mRNA expression level of IFN-γR was significantly lower in chronic urticaria patients than in healthy controls（P＜0.05）. Conclusion There is a differentiation bias of Th cells in peripheral blood of patients with chronic urticaria,which might be a key factor for its possible immunopathogenesis.