In order to examine whether variation in interleukin-10 promoter polymorphism would predict the likelihood of sustain response of chronic hepatitis B to treatment with interferon alfa (IFN-α), the inheritance of 3 biallelic polymorphisms in the IL-10 gene promoter in patients with 52 chronic hepatitis B were determined by polymerase chain reaction (PCR)-bared techniques, restriction enzyme digestion or direct sequencing. The gene discussed is IL10; the disease is chronic hepatitis B virus infection.