Objective[|]This study aimed to determine the frequency of HBV reactivation and the potential predictive factors in resolved hepatitis B virus (HBV) patients [hepatitis B surface antigen (HBsAg)-negative and antibody to hepatitis B core antigen (anti-HBc)-positive patients] who received rituximab-containing chemotherapy for B-cell lymphoma.[¤]Materials and Methods[|]A retrospective examination was performed for HBV-related markers in 106 patients before and after receiving rituximab-containing chemotherapy for CD20-positive B-cell lymphoma.[¤]Results[|]Of the 106 patients with CD20-positive B-cell lymphoma who received rituximab-containing chemotherapy, 98 were HBsAg negative and 8 were HBsAg positive; among the 98 patients, 64 (65.7%) were anti-HBc negative and 34 (34.7%) were anti-HBc positive. Of the 34 CD20-positive B-cell lymphoma patients with resolved HBV infection who received rituximab-containing chemotherapy, 26 (76.5%) were anti-HBsAg antibody (anti-HBs) positive and 8 (23.5%) were anti-HBs negative. Of these 8 anti-HBs-negative patients, HBV reactivation occurred in 4 (50%) patients; no HBV reactivation was observed in any of the 26 anti-HBs-positive patients. Compared with the anti-HBs-positive patients, the rate of HBV reactivation in B-cell lymphoma patients who were anti-HBs negative and had resolved HBV infection revealed a highly significant relationship (p<0.001).[¤]Conclusion[|]HBV reactivation occurred in 50% of the CD20-positive B-cell lymphoma anti-HBs-negative patients with resolved HBV infection who had received rituximab-containing chemotherapy and in none of the anti-HBs-positive patients. This indicates that anti-HBs negativity in the patients with resolved HBV infection is an important risk factor, and the antiviral prophylaxis should certainly be administered to such patients.[¤]