Over the past 12 years, the poxvirus vector technology has provided scientists with valuable reagents to achieve high‐level expression of proteins, to address questions of structure‐function relationship of specific polypeptides, to investigate the immunobiology of specific pathogens, and to develop recombinant vaccine candidates. It is this last role that has drawn enthusiasm from the medical community because of the potential this technology has to provide novel approaches for addressing urgent needs in human and veterinary medicine. From one perspective, the safety issues surrounding the use of vaccinia‐based vaccine candidates have been addressed with the development of the NYVAC and ALVAC vectors. Evaluation of these novel poxvirus vectors are in progress to determine their potential impact on cancer and infectious disease. J. Leukoc. Biol. 58: 1–13; 1995.