Attenuated pseudorabies viruses are provided which comprise DNA including a sequence essential for replication of the attenuated virus, at least a portion of which is present in a sequence essential for replication of a naturally-occurring pseudorabies virus, and at least one foreign DNA sequence adapted for expression in a host and encoding an amino acid sequence which is antigenic in the host. These viruses are useful as vaccines for immunizing animals against pseudorabies virus disease and other pathogens.The invention also provides methods of preparing attenuated pseudorabies viruses containing at least one foreign DNA sequence and methods of immunizing animals with vaccines comprised of these viruses.