Abstract: Objective To report and analyze a case of using pegylated interferon alpha-2 a injection(Peg-IFN-α-2 a) in the treatment of a child with chronic hepatitis B(CHB). Methods Peg-IFN-α-2 a was used to treat a CHB child with positive hepatitis B e antigen(HBe Ag). Clinical and laboratory data were collected and analysed during treatment and follow-up. Results After 24 weeks of treatment with Peg-IFN-α-2 a,both HBe Ag and hepatitis B surface antigen(HBs Ag) seroconversion preceded,and hepatitis B virus(HBV) DNA dropped from 6. 20 lg IU/ml to the line that undetected. Aminotransferase(ALT) decreased to normal level,and HBV surface antibodies(anti-HBs) were present. The child experienced fever and neutropenia symptoms during treatment. Conclusion Using Peg-IFN-α-2 a as antiviral drug might provide a safe and effective treatment option for children with CHB. It would provide theoretical evidence for subsequent development of antiviral treatment protocol for them.