Acellular pertussis vaccine has been used widely in Korea since 1984. However, because many of the former generations were not inoculated with pertussis vaccine, they may infect infants with pertussis. With this background, we investigated the prevalence of pertussis antibodies in all age groups. Enzyme-linked immunosorbent assay (ELISA) to assess IgG antibodies to pertussis toxin (PT) and filamentous hemagglutinin (FHA) and bacterial agglutination (BA) to assess antibodies to agglutinogen were compared on 842 serum samples which were donated from 11 hospitals in Seoul area. In comparison with age groups under 20 years, antibodies of adults against PT and FHA were maintained. But antibodies against agglutinogen showed no pattem in all age groups. Antibodies to PT were correlated with antibodies to FHA. There was no significant difference in antibody levels between male and female (p<0.05).