Seroepidemological investigation of antibodies to Legionella species in 500 healthy individuals from a single geographical location in Korea was conducted by indirect fluorescent antibody assay (IFA). Considering an antibody titer of > or =1:128 as positive reaction, 15.2% of total sera were positive. In males and females older than 40 years old, levels of IgM and IgG were 1.2% and 14%, respectively. The sera with antibody titers of > or =1:128 to Legionella species accounted for 85 sera, and 9 sera of these were reacted to more than one Legionella species. Reactivity to L. bozemanii, L. micdadei, L. longbeachae, L. pneumophila sg 6, and L. gormanii were 32.9%, 20%, 15%, 10.6%, and 8%, respectively. However, L. pneumophila sg 1, sg 2, and sg 3 did not react to any sera. Serological analysis revealed that the level of antibody in response to L. bozemanii was more prevalent than L. pneumophila. Our results suggest that the antibodies of non-L. pneumophila species, such as L. bozemanii, may be highly prevalent in healthy population within Korea. Although conclusions based on the findings of this study must be cautiously considered given that the population sampled were sourced from a single province, we have added to the knowledge base of serodiagnosis of infections due to non-L. pneumophila species in Korea.