Young as well as adult free living Norvegian rats (Rattus norvegicus) were highly susceptible to intranasal, intradermal and natural infections with the ratpox virus belonging to genus Orthopoxvirus. Disseminated disease occurred in infected rats due to generalization of the virus to internal organs. In survivors, virus was excreted for a longer period of time (more than 1 month) in faeces and urine.