Treatment cessation in chronic HBV infection may be durable in certain patient subgroups before hepatitis B surface antigen (HBsAg) seroclearance. The role of serum HBV RNA in determining treatment cessation suitability has not been well-investigated.Nucleos(t)ide analogue (NUC) treatment was discontinued in non-cirrhotic patients with chronic HBV with serum HBsAg <200 IU/mL and fulfilling internationally recommended criteria for treatment cessation. Patients were monitored till 48 weeks with baseline and serial measurements of serum HBsAg, HBV RNA and hepatitis B core-related antigen. NUCs were resumed when HBV DNA reaches >2000 IU/mL regardless of alanine aminotransferase (ALT) levels.114 entecavir-treated patients (median age 58.4 years, median serum HBsAg 54.4 IU/mL) with median treatment duration of 6.7 years were recruited. The 48-week cumulative rate of HBV DNA >2000 IU/mL was 58.1%. End-of-treatment serum HBV RNA and off-treatment serial HBV RNA were both independently associated with HBV DNA >2000 IU/mL (HR 2.959, 95% CI 1.776 to 4.926, p<0.001; HR 2.278, 95% CI 1.151 to 4.525, p=0.018, respectively). Patients with HBV RNA ≥44.6 U/mL had a cumulative 48-week rate of 93.2%, while combining HBV RNA undetectability and HBsAg <10 IU/mL had a cumulative 48-week rate of 9.1%. 24 patients (38.7%) developed off-treatment ALT elevation, highest peak ALT was 1515 U/L. 8 patients (median serum HBsAg 2.6 IU/mL) developed HBsAg seroclearance.Serum HBV RNA measurement is essential for deciding on entecavir cessation in patients with chronic HBV, especially with low HBsAg levels. Patients can be stratified on their risk of off-treatment relapse based on both viral determinants.NCT02738554.