Twenty-five hybridoma cultures secreted monoclonal antibodies directed against the glycoprotein of rabies or rabies-related viruses. The antibodies had different specificities for the glycoproteins of eight rabies and rabies-related viruses. They could be classified into fourteen groups which probably correspond to different antigenic determinants on the glycoproteins. These hybridomas when used in either radioimmunoassay (RIA) or in neutralization tests allow differentiation of laboratory strains of rabies virus from each other as well as from the rabies-related viruses.