Objective To explore the relationship between the antiviral effect and peripheral blood mononuclear cell (PBMC) hepatitis B virus (HBV) DNA when the patients reach the standard of withdrawal of antiviral therapy in chronic hepatitis B (CHB).Methods Ninety CHB patients treated with interferon(n=44) or nucleot (s) ide(n=46) who reached the standard of withdrawal of antiviral therapy were recruited.HBV DNA levels in PBMCs were tested at the end of treatment,and its relationship with serum HBV DNA level before treatment in PBMC HBV DNA positive group and negative group were compared.The correlation between HBV DNA in PBMCs at the end of treatment and relapse were explored.Measurement data were analyzed by student t test and enumeration data were analyzed by X2 test.Results Among 90 patients,67(74.4%) were PBMC HBV DNA negative at the end of treatment,and 23(25.6%) were positive.The serum HBV DNA positive conversion rate in PBMC HBV DNA negative patients was 13.4%,which were significantly lower than that in positive group (73.9%) (X2=30. 4873, P<0.01 ). There were no significant differences of alanine aminotransferase (ALT) levels when hepatitis flare (t=0. 8729, P=0. 3913) and relapse time (t=1. 9222, P=0. 0665) between PBMC HBV DNA negative group and positive group after withdrawal of therapy, while the serum HBV DNA rebound was greater in positive group than that in negative group (t=2. 7493, P=0. 0112). There were five patients who achieved hepatitis B surface antigen (HBsAg) seroconversion, whose PBMC HBV DNA were all undetectable, and none relapsed during follow-up for 6-12 months. The pretreatment HBV DNA as level in PBMC HBV DNA positive was (7.2±1.1) lg copy/mL, which was much higher than that in negative group[(5.2±2.1) lg copy/mL] (t=4. 3557, P<0.01). Conclusions In patients who reach the standard of drug withdrawal,PBMC HBV DNA at the end of treatment is an important predictor for durability of antiviral therapy in CHB.