Rituximab, an anti‐CD20 monoclonal antibody, is associated with an increased risk of hepatitis B virus (HBV) reactivation. This study aimed to determine the predictive factors for rituximab‐related HBV reactivation in resolved hepatitis B patients, defined as HBsAg‐negative, anti‐HBc‐positive, and undetectable HBV DNA. Among 840 consecutive patients with CD20‐positive B‐cell lymphoma who received rituximab‐based chemotherapy from 2003 through 2014 at Seoul National University Hospital, 732 patients were excluded because either anti‐HBc was not assessed or they were HBsAg‐seropositive. This retrospective study included 108 resolved hepatitis B patients. During a median 33.5‐month follow‐up period, eight cases of HBV reactivation occurred only among the patients with low anti‐HBs titers (<100 mIU/ml) at baseline and those who did not receive antiviral prophylaxis. Using multivariate analyses, antiviral prophylaxis and baseline anti‐HBs titers were the protective factors for HBV reactivation (hazard ratio [HR], 0.90 and 0.95, respectively). Among those who did not receive antiviral prophylaxis, patients with high baseline anti‐HBs (≥100 mIU/ml) experienced significantly lower risk of HBV reactivation (HR, 0.49; P = 0.006) than the patients with low baseline anti‐HBs (<100 mIU/ml) whose cumulative HBV reactivation rates at 6 and 24 months after chemotherapy were 8.3% and 17.3%, respectively. High anti‐HBs titer at baseline and antiviral prophylaxis prevented HBV reactivation, suggesting antiviral prophylaxis should be considered according to baseline anti‐HBs titer. Meticulous follow‐up for ALT and HBV DNA without antiviral prophylaxis might be possible for the patients with high baseline anti‐HBs (≥100 mIU/ml). J. Med. Virol. 88:1010–1017, 2016. © 2015 Wiley Periodicals, Inc.