Watanabe T, et al. - Experts gauged the incidence and risk factors for hepatitis B virus (HBV) reactivation in rheumatoid arthritis (RA) patients with resolved HBV receiving biological disease-modifying antirheumatic drugs (bDMARDs). They reviewed rheumatoid arthritis patients in whom bDMARD therapy was initiated in our departments from April 2009 to July 2016. In 4.6% of RA patients with resolved HBV during the treatment with bDMARDs, occurrence of HBV reactivation was seen and the absence of anti-HBs may be a risk factor for the reactivation of resolved HBV. Significantly higher incidence of HBV reactivation was seen in patients who were negative for anti-HBs.