To investigate the incidence and risk factors of hepatitis B virus (HBV) reactivation in HBV surface antigen (HBsAg)-/ HBV core antibody (HBcAb)+ patients who underwent rituximab (RTX) therapy for rheumatoid arthritis (RA). From January 2000 through December 2017, a total of 134 RA patients with various HBV serostatuses who received RTX at Dalin Tzu Chi Hospital were screened. Finally, 50 HBsAg-/HBcAb+ patients were enrolled in this retrospective study. Baseline characteristics, comedications, and the occurrence of HBV reactivation were recorded. Four HBsAg-/HBcAb+ RA patients (8%; 4/50) experienced HBV reactivation after treatment with RTX. Hepatitis flare-up occurred in 2 of these 4 patients, with a fatal outcome in one. HBV reactivation occurred approximately 1-4 years after the first dose of RTX and 0.5-1.5 years after the last one. In HBsAg-/HBcAb+ patients, HBV reactivation was significantly more common in those who were HBV surface antibody (HBsAb)- at baseline than in those who were HBsAb+ (30% vs 4%; p = 0.02). A history of adalimumab use was associated with HBV reactivation (100% vs 39%; p = 0.02). A moderate risk of HBV reactivation was observed in HBsAg-/HBcAb+ RA patients receiving RTX therapy. The reactivation may induce acute hepatitis and even death. To reduce the risk of HBV reactivation, regular monitoring of liver function is insufficient; monitoring of viral load and HBsAg or prophylaxis with antiviral therapy should be considered.