Isolates of rabies virus from terrestrial animals in six geographically separate rabies enzootic areas of the United States were examined with a panel of monoclonal antibodies to the viral N protein. Characteristic differences in immunofluorescence reactions permitted the formation of five antigenically distinct reaction groups from the 328 isolates tested. Distinctive reaction patterns were also identified for isolates from four species of bats. These observations were used to determine the role of infected bats in 19 cases of rabies that had occurred in terrestrial animals living in areas free of enzootic rabies in terrestrial wildlife and to estimate the contribution of infected bats to rabies in cats and foxes in the United States. The findings suggest that monoclonal antibodies can be used to study the prevalence, distribution, and transmission of rabies among wildlife species.