This open-label, single-arm, multicenter study will evaluate the efficacy and safety of adding Pegasys (peginterferon alfa-2a) to nucleos(t)ide analogue (NAs) treatment in participants with HBeAg-negative chronic hepatitis B genotype D showing stable HBV DNA suppression. After a 12-week Lead-in period on treatment with NA, participants with a HBsAg decline <0.5 log10 IU/ml will enter the Add-on period to receive Pegasys 180 mcg subcutaneously weekly for 48 weeks in addition to their current NA treatment. Follow-up will be a further 48 weeks, during which the participants will continue their NA treatment.