The present invention relates to recombinant vaccinia viruses derived from the modified vaccinia virus Ankara (MVA) and containing and capable of expressing foreign genes which are inserted at the site of a naturally occurring deletion in the MVA genome, and the use of such recombinant MVA viruses for the production of polypeptides, e.g. antigens or therapeutic agents, or viral vectors for gene therapy, and the use of such recombinant MVA viruses encoding antigens as vaccines.