Abstract: The invention relates to DNA from fowlpox virus (FPV) providing a non-essential region for the insertion of foreign genes thereinto and thence the construction of a vector for homologous recombination with a wild type FPV, whereby the resulting recombinant FPV can be used for vaccination of animals, especially chickens. In this invention, the non-essential region consists substantially of a length of DNA from the long unique sequence of the terminal inverted repeat (TIR) of FPV or from the region at FPV which corresponds approximately to the HindIII D fragment genes D8 and D9 in vaccinia virus.