BACKGROUND/AIMS: Administration of hepatitis B immunoglobulin (HBIG) initially after liver transplantation of hepatitis B patients is considered important to prevent reinfection reliably. However, dosing schedules differ considerably between centers. We measured HBsAg, anti-HBs and HBV DNA kinetics to create a rational basis for dosing schemes. METHODS: Thirteen patients (group A) received 10,000 IU HBIG in the anhepatic phase followed by 10,000 IU daily until HBsAg became negative, whereas five patients (group B) received 20,000 IU followed by 5000 IU every 30 min. RESULTS: HBsAg levels at time of transplantation ranged from 0.12 to 12,990 IU/ml. Correlations between initial HBsAg and HBIG required to decrease HBsAg below 1 IU/ml were high in groups A and B (r=0.97, p