Background: Small bowel transplant with or without a liver graft (SBTx ± LTx) for children with intestinal failure involves checking their immunity to a range of microorganisms, including hepatitis B virus (HBV), at the time of assessment. HBV vaccination in the United Kingdom is recommended for transplant candidates. The aim of this audit was to find out how many SBTx ± LTx candidates received HBV vaccination before transplantation and how the timing of vaccination influenced the development of immunity. Materials and Methods: Retrospective review of case notes and hospital microbiology database formed the basis of the study. Vaccination history and serology were available in 56 of 87 subjects who had SBTx ± LTx. Results: All patients were seronegative for HBV when assessed for transplant. HBV vaccination was started before transplant in 25 children and after transplant in 31. Eight children died posttransplant before their immunity could be checked, but of the 48 survivors, 20 children developed immunity, of whom 13 (65%) received at least 1 vaccination before SBTx ± LTx (P = .008). Lack of response to HBV vaccine was significantly associated with isolated bowel transplantation and intensification of immune suppression. Of 11 children, 5 lost hepatitis B surface antibody (HbsAb), and 28 never made HBsAb, despite repeated vaccinations. Conclusion: Our study clearly shows that HBV vaccine before transplant is more effective. In line with renal failure patients, we suggest that children with chronic intestinal failure receive HBV vaccine when clinically stable, before referral for transplant. Higher-dose vaccines, accelerated schedules, and more frequent booster vaccinations are also strategies that may improve HBsAb levels after transplant.