Abstract: Objective To evaluate the efficacy of long term and low dose α-interferon in treatment of patients with chronic hepatitis C co-infected with HGV.Methods 32 enrolled patients with chronic hepatitis C co-infected with HGV were divided into two groups treated with α-interferon or placebo.Serum ALT,HGV RNA and HCV RNA were determined before and 3 and 6 months after therapy.Results The ALT level of the α-interferon group decreased steadly from the initial level of 119 6IU/L to 56 2IU/L at 6 month after treatment,significantly lower as compared with that of the placebo group(126IU/L).The HGV RNA negative seroconversion rates at 3 and 6 months after treatment were 64.7% and 64.7%,respectiely,as compared with 60.0% and 66.7% in the placebo group.No significant difference was found between the two groups.17 patients treated with α-interferon were followed up for 6 months.The ALT maintained athigh levels(154IU/L,168IU/L and 84IU/L,respectively)in the 3 patients with negative seroconversion of HGV RNA and persistent reactivity of HCV RNA.However,the ALT level returned to the normal(25IU/L,20IU/L and 20IU/L,respectively)in the 3 patients with persistent reactivity of HGV RNA and negative seroconversion of HCV RNA.HGV infection is self limited,and α-interferon has no significant efficacy on the clearance of HGV RNA.The ALT level correlates with HCV RNA reactivity in serum,but not with HGV RNA.Conclusion HGV does not seem to cause the liver damage.