Patients who undergo transplantation for hepatitis B virus (HBV)-related diseases are treated indefinitely with hepatitis B hyperimmunoglobulin (HBIG) to prevent endogenous HBV reinfection of the graft. Active immunization with standard hepatitis B vaccines in these patients has recently been reported with conflicting results. Two groups of 10 liver transplant recipients on continuous HBIG substitution who were hepatitis B surface antigen (HBsAg) positive and HBV DNA negative before transplantation were immunized in a phase I study with different concentrations of hepatitis B s antigen formulated with the new adjuvants 3-deacylated monophosphoryl lipid A (MPL) and QuiZhja saponaria (QS2 1) (group I/vaccine A: 20 pg HBsAg, 50 pg MPL, 50 p g QS21; group II/vaccine B: 100 p g HBsAg, 100 pg MPL, 100 p g QS21). Participants remained on HBIG prophylaxis and were vaccinated at weeks 0, 2, 4, 16, and 18. They received 3 additional doses of vaccine B at bimonthly intervals if they did not reach an antibody titer against hepatitis B surface antigen (anti-HBs) greater than 500 IU/L. Sixteen (8 in each group) of 20 patients (80%) responded (group I: median, 7,293 1U/L; range, 721-45,811 IU/L anti-HBs; group 11: median, 44,549 IU/L; range, 900-83,121 IU/L anti-HBs) and discontinued HBIG. They were followed up for a median of 13.5 months (range, 6-22 months). The vaccine was well tolerated. In conclusion, most patients immunized with the new vaccine can stop HBIG immunoprophylaxis for a substantial, yet to be determined period of time. (HEPATOLOGY 2003;38:811-819.) epatitis B virus (HBV) infection with acute liver failure or liver cirrhosis is the indication for liver H transplantation in 10% to 20% of liver transplant recipients.' These patients face a high risk of endogenous HBV reinfection without continuous postoperative immunoprophylaxis. The reinfection rate in preoperatively HBV DNA-positive patients is about 80% and about 50% in HBV DNNhepatitis B e antigen (HBeAg)-negative recipients.2