Exact titration of anti-HBs with mIU/mL unit is necessary in evaluating the success of HBV vaccination or in making a decision to increase the dose of HBV vaccination. Data of distribution of anti-HBs titers can contribute to cutting of public health costs by reducing unnecessary HBV booster doses. Moreover, anti-HBc is also an important marker for differentiation of vaccination-induced anti-HBs from infection-acquired anti-HBs. However, not much study about these subjects has been done in Korea. So we evaluated anti-HBs associated with anti-HBc and vaccination history. HBsAg and anti-HBs tests were done in 1,465 cases. The positive rates of HBsAg and anti-HBs were 4.5% and 74.6%, respectively. Anti-HBs positive rate was higher in the vaccinated group than that in the non-vaccinated group. The rates of anti-HBs positive cases with lower titers (10- or = 100 mIU/mL) were 68.1%. This suggested about 70% of anti-HBs-positive Korean adults (about 53% of the general adult population) have long-lasting immunity against HBV infection and may not require booster doses of HBV vaccination for a long time. Anti-HBs titers in the vaccine-induced anti-HBs group were higher than those in the infection-acquired anti-HBs group. No statistical differences were noted between male and female or among age groups. 25.7% of the HBsAg (-)/anti-HBs (-) group showed anti-HBc positive and HBV-DNA was detected in 11.1% among HBsAg (-)/anti-HBs (-)/anti-HBcAb (+) cases. Further study about post vaccination anti-HBs titer decay in Korean should be performed to help cut vaccination costs.