Three groups of monoclonal antibodies (mAbs) were produced that would be useful for immunochemical typing and diagnosis of infections due to Bordetella species, and for the structural analysis of their lipopolysaccharides. PP6, a representative of the first group, recognizes an epitope shared by smooth-type Bordetella parapertussis and Bordetella bronchiseptica lipopolysaccharides (LPS). This epitope is carried by structurally identical polymeric O-chains (POC) present on both LPS molecules. PP8 and PP9 are representatives of the second group of mAbs. The interaction of PP8 and PP9 with B. parapertussis and B. bronchiseptica LPS requires POC, but periodate-sensitive sugar units of the core are also involved in the binding. The mAb BRg1 belongs to the third group, and specifically recognizes B. bronchiseptica LPS. Binding and inhibition studies with various Bordetella LPS molecules, and with their polysaccharide fragments, indicated that BRg1 interacts with a structure located at the hinge between the POC and a core region of the B. bronchiseptica LPS containing periodate-resistant sugars. This suggests that the structures of the hinge regions of the B. parapertussis and B. bronchiseptica LPS are different.