Objective:To detect hepatitis B virus pre-core region 1896 site mutation in cases of chronic hepatitis B and investigate its relationship with IFN treatm-ent.Methods:The hepatitis B virus pre-core region 1896 site mutation was detected in 200 patie-nts with chronic hepatitis B,the changes of hepatitis B virus variant after IFN treatment and the of IFN were also observed.Results:The mutation rates before interferon treat-ment were 19% in 200 patients with chronic hepatitis B.After treatment,the effective rates were 60% and 50% in patients with Chronic Hepatitis B and virus Infection,respectly.The effective rates in experimental group was significantly higher than that in control group(P<0.001).There was no difference in the effective rates of IFN treatment between patients with Chr-onic Hepatitis B virus infection and patients with virus infection(P>0.05).Conclusions:IFN therapy was not correlated with genomic variability of the pre-core region.using IFN was a not only for cases with virus infection but also for cases with virus infection.