Hepatitis B core-related antigen (HBcrAg), a new serum marker, may be useful in monitoring chronic hepatitis B infection. HBcrAg was measured in 175 hepatitis B e antigen-positive patients treated with entecavir (ETV) with or without peginterferon (PEG-IFN) add-on therapy. Decline in HBcrAg was stronger in patients with vs. without combined response (ETV: -3.22 vs. -1.71 log U/mL, p <0.001; PEG-IFN add-on: -3.16 vs. -1.83 IU/mL, p <0.001) and in patients with vs. without hepatitis B surface antigen (HBsAg) response (ETV: -2.60 vs. -1.74 log U/mL, p <0.001; PEG-IFN addon: -2.38 vs. -2.15 log U/mL, p = 0.31). HBcrAg was associated with combined response (adjusted odds ratio 0.3, 95% confidence interval 0.2-0.5, p <0.001), but was not superior to quantitative HBsAg (qHBsAg). (C) 2016 Published by Elsevier Ltd on behalf of European Society of Clinical Microbiology and Infectious Diseases.