Fowlpox virus, the prototypic virus of the genus Avipoxvirus has a natural host range limited to avian species. As such, fowlpox virus provides a suitable candidate for the development of a species-specific recombinant viral vector. This paper reports the development of a fowlpox virus recombinant expressing the haemagglutinin molecule from a highly virulent avian influenza virus. On immunization of chickens and turkeys with the recombinant, protection is afforded against a lethal challenge with either the homologous or a heterologous influenza virus strain.