Lamivudine combined with Hepatitis B immune globulin (HBIg) prevents post liver transplant (LT) HBV recurrence. The study was designed to assess the impact of lamivudine on hepatitis B antibody (anti-HBs) and dosage requirements of intravenous 5% HBIg (Nabi-HB®) in the first 36 weeks post LT. Adults undergoing LT for chronic HBV received lamivudine prior to or at LT, and IV HBIg 20,000 IU on day of LT, 10,000 on days 1-7, weeks 4 and 8, and 5,000 every 4 weeks thereafter. Replicative status based on serum HBV DNA (> 5 pg/mL = replicator (R) or ≤ 5 pg/mL = nonreplicator (N) was determined at initiation of lamivudine (R or N) and within 2 weeks of LT (r or n), resulting in 3 groups: Nn, Rn, and Rr. Between December 1999 and May 2001, 30 patients (10 Nn, 13 Rn, 6 Rr, and 1 unknown), mean age of 52 years underwent LT. HBsAg neutralization was achieved with anti-HBs > 300 IU/L during week 1 and > 200 IU/L during weeks 2-12. All but one patient were HBsAg-negative on last follow-up. Pre-LT suppression of HBV replication resulted in similar dose requirements and pK in the Rn and Nn groups within 1 week after LT. Comparatively, the Rr group had greater HBIg requirements during weeks 1-12 due to greater anti-HBs clearance and shortened t1/2 during the entire 36-week follow-up. In conclusion, this study provides a rationale for the use of lower HBIg doses in HBV patients with suppressed replication undergoing LT.