CONTEXT: Bleeding in severe hemophilia B is minimized by factor IX (FIX) replacement either as once- or twice-weekly prophylaxis. Recent trials have focused greater interest on once-weekly prophylaxis using standard recombinant FIX (rFIX) or enhanced half-life rFIX. Limited data are available on optimal prophylaxis regimens of FIX replacements for patients with hemophilia B.AIMS: This study aimed to evaluate the efficacy of once-weekly prophylaxis compared with twice-weekly prophylaxis with BeneFIX (rFIX) in children with severe hemophilia B.SETTINGS AND DESIGN: This study is a retrospective, two-period study from January 2012 to December 2017.SUBJECTS AND METHODS: The study assessed the efficacy of 3-year twice-weekly prophylaxis with BeneFIX (rFIX) in patients with severe hemophilia B followed by 3-year once-weekly prophylaxis, then comparing once weekly versus twice weekly at a given period. The primary efficacy endpoint was the annualized bleeding rate (ABR) and the secondary endpoint included Functional Independence Score for patients with Hemophilia (FISH) scoring.RESULTS: There was no statistically significant difference in the bleeding per year and the joint bleeding per year between once- and twice-weekly prophylactic treatment regimens (P > 0.05). There was no statistically significant difference in ABR between once- and twice-weekly prophylaxis, 11.9 and 9.1 bleeds per year, respectively (P > 0.05). In addition, there was no statistically significant difference in the hospitalization and school absence between once- and twice-weekly prophylactic treatment regimens (P > 0.05). There was no statistically significant difference in FISH score between once- and twice-weekly protocol (P > 0.05), but factor consumption was significantly higher in the twice-weekly protocol compared with once-weekly protocol (P < 0.001).CONCLUSIONS: Once-weekly prophylaxis was effective and tolerated prophylaxis for most patients included in this study. Once-weekly prophylaxis is an effective alternative to twice-weekly prophylaxis, and both the regimens reduce ABR in children with severe hemophilia B.