Fimbrial proteins are important for adhesion and colonization of Bordetella bronchiseptica in the upper respiratory tract. In this study, determination of immunogenicity of the fimbrial proteins isolated from different strains of B. bronchiseptica and their protective efficacy against fetal challenge was aimed. For this purpose, fimbrial proteins of seven standard strains and clinical isolates of B. bronchiseptica were partially purified by gel filtration chromatography and analysed by SDS-PAGE. In microagglutination test, whole cell F415 was used as the antigen and the agglutination of sera from mice immunized with the purified fimbrial proteins was observed at titers of 1:128 for strains 219 and 4617 and the isolate CA; 1:256 for strain F415 and the isolate UK7; 1:512 for the isolate UK6 and 1:4096 for strain 3036. In addition, by ELISA against F415 fimbrial antigen, the antifimbriae antibody levels of the immune mouse sera were observed at serum dilutions of 1:6400 for UK7; 1:3200 for UK6, F415 and 3036; 1:1600 for CA; 1:800 for 219 and 1:400 for 4617. The protective values of the fimbrial proteins against fetal challenge with strain F415 in mice immunized with the fimbrial proteins (2x25 mu g/dose) were; 100% for F415 and 3036, 84% for UK6 and 50% liar UK7, but no protection was observed with the other strains and isolates. In conclusion, fimbrial antigens were determined to have important protective efficacy and anti-fimbriae antibody levels were found correlated with that protective efficacy.