Monoclonal antibodies (MAbs) to Burkholderia cepacia were produced from mice immunized with inactivated whole-cell antigen. For screening of resulting MAbs an enzyme-linked immunosorbent assay (ELISA) was used. A stable hybridoma cell line (BC-2) producing specific antibodies to a 64 kDa somatic antigen from B. cepacia was established. In ELISA and immunoblotting analysis the MAb BC-2 recognized all tested strains of B. cepacia whereas no cross-reaction with 32 Pseudomonas aeruginosa strains was found. From a wide range of other bacteria only strains of the species Burkholderia mallei, Burkholderia pseudomallei, and Burkholderia gladioli showed cross-reactions. The MAb BC-2 will be used to develop a diagnostic assay for the identification of B. cepacia and B. gladioli, important agents of nosocomial infections in immunocompromised patients suffering especially from cystic fibrosis (CF).