In patients who have resolved hepatitis B virus (HBV) infection, treatment of rheumatoid arthritis (RA) can result in reappearance of hepatitis B surface antigen (HBsAg), called reverse seroconversion. We investigated clinical features and outcomes of reverse seroconversion in patients who received immunosuppressant or biologic therapy for RA.We identified 1494 patients with RA (925 who resolved HBV infection) and available data on levels of antibody to HB core antigen and HBsAg who had attended Taipei Veterans General Hospital from January 2007 through December 2017. We identified 17 cases (median age, 66 years) who were negative for HBsAg before treatment of RA and reverse seroconversion (HBsAg reappearance) after glucocorticoid treatment (n=13) and/or biologic therapy (adalimumab, n=2; etanercept, n=1; rituximab, n=9; or abatacept, n=4). Four patients were positive for antibodies against HBsAg (seroconverted) before the immunosuppressive treatment.The median time from immunosuppressive treatment to reverse seroconversion was 120 months (range, 20-264 months), whereas the time from biologic therapy treatment to reverse seroconversion was 66 months (range, 10-105 months). After reverse seroconversion, 8 individuals (47.1%) were positive for HB e antigen; 9 cases (52.9%) did not have a flare of alanine transaminase. However, 3 patients (17.6%) developed liver decompensation.In patients who resolved HBV infection and received immunosuppressant treatment of RA, risk of reversal of seroconversion is low but persists for up to 10 years. Patients with RA who previously resolved HBV infections should be monitored for levels of HBsAg and HBV DNA once immunosuppressive treatment of RA begins.