Hepatitis B (HB) vaccinations given once weekly for 3 weeks can provide early seroprotection. This study compared immune responses induced by the accelerated (A; days 0, 10, 21) and classic (C; days 0, 28, 56) HB vaccination schedules. Two hundred seventy healthy subjects (95 men, 175 women) with a mean age of 23.8 years received 3 doses of GenHevac B, a recombinant vaccine produced in mammalian cells. The subjects were randomly assigned to schedules A or C. A booster dose was given 1 year later. One month after the third dose, 70% (schedule A) and 92% (schedule C) of the subjects were seroprotected and 100% (A) and 99% (C) had developed anti-pre-S2 antibodies. Before booster injections, 93% (A) and 95% (C) of the subjects were seroprotected, and 1 month after the booster, almost all subjects were seroprotected. A 3-week HB vaccination schedule with GenHevac B can confer early protective immunity lasting up to 1 year.