Objective:To study the role of FOXP3 in patients with acute infection of hepatitis C virus. Methods:Flow cytometry was used to determine the number of CD4+CD25+T cells in peripheral blood;the levels of the Th1/Th2 cytokines secretion of PBMC in patients and healthy donors were detected by ELISA;the expression of FOXP3 mRNA was measured by RT-PCR. Results:CD4+CD25+T cells comprised (28.2±2.1)% of peripheral CD4+T cells in the blood of acute hepatitis C virus infected patients,and it was significantly higher than that of healthy controls(2.7±0.7)%(P=0.032). CD4+CD25+T cells in the peripheral blood of acute hepatitis C virus infected patients highly expressed FOXP3. Compared with the cytokines levels of normal control,the levels of IL-10 was notably increased(P < 0.01) while IL-2 was not detected in the culture supernatant of PBMCs from patients. Conclusion:Patients with acute hepatitis C virus infection showed an increased number of FOXP3,which suppressed Th1 response.