Objective To analyze the efficacy of entecavir (ETV) combined with Peg IFNα-2b in chronic hepatitis B ( CHB) patients with low levels HBsAg following initial ETV treatment.Methods Sixty-nine CHB outpatients achieving serum HBsAg ＜2 000 IU/mL and HBV DNA＜100 IU/mL following initial ETV treatment in Pujiang People's Hospital and the First Affiliated Hospital of Zhejiang University School of Medicine from January 2014 to January 2016 were enrolled.Patients were randomly assigned in two groups: 39 patients in combination group received ETV (0.5 mg/d ) and Peg IFNα-2b (1.5 μg· kg－1· week －1, hypodermic injection), and 30 patients in ETV group received ETV (0.5 mg/d) alone.Serum HBsAg quantification, negative conversion rate of HBsAg and HBeAg , and levels of aminotransferase (ALT) were measured at baseline , 12th, 24th, 48th, 72th and 96th week after treatment.Results The levels of HBsAg in the combination group decreased gradually with the prolongation of therapy , which were lower than those in ETV group 24 week after treatment (Z＝－2.566,P＜0.05),and at 48th, 72th and 96th week (Z＝－3.499,－3.825 and －3.864,P＜0.01).Clearance of HBsAg appeared in the combination group at 24th week,the clearance rates were 7.70%(3/39) and 28.20%(11/39) at 24th and 96th week, respectively;while the clearance of HBsAg occurred in ETV group at 96th week, the clearance rate was only 3.30%(1/30).The negative conversion rates of HBsAg in combination group were higher than those in ETV group at 48th,72th and 96th week (P＜0.05 or＜0.01).In the combination group, there were 11 cases of clinical cure , 11 cases of clinical efficacy and 17 cases of clinical effectiveness , while there were 1, 1 and 28 cases in ETV group,respectively.The treatment effect of the combination group was better than that of ETV group(χ2＝18.496,P＜0.01).Serological conversion rates of HBeAg were 30.00%(6/20) and 65.00%(13/20) in combination group at 12th and 96th week, while those were 11.11%(2/18) and 22.22%(4/18) in ETV group at 48th and 96th week.There were significant differences in the HBeAg serological conversion rates at 12th, 24th, 72th and 96th week between two groups (P＜0.05 or ＜0.01). The levels of ALT in combination group increased at 12th and 24th week, which had significant difference compared with ETV group (Z＝－1.236 and －2.658,P＜0.05), and the ALT levels gradually declined 48 week after treatment in combination group and there were no statistical differences between two groups at other time points.The ETV combined with Peg IFNα-2b and low baseline HBeAg levels were associated with the clearance rate of HBsAg (both P＜0.01).Conclusions CHB patients with low HBsAg levels following initial ETV monotherapy can achieve high negative conversion rate of HBeAg and HBsAg with the combination treatment of ETV and Peg IFN α-2b.