Tests to determine the antigenic relationship between three viruses of the rabies serogroup, rabies virus, Lagos bat virus, and IbAn 27377 virus, were conducted in mice. Mice vaccinated intracerebrally or intraperitoneally with either of two strains of rabies virus resisted challenge with Lagos bat virus. Similarly vaccinated mice resisted challenge with IbAn 27377 virus to only a slight degree. Mice vaccinated intraperitoneally with Lagos bat or IbAn 27377 virus resisted homologous but not heterologous viral challenge.