This review is aimed at bringing DNA vaccines into perspective with regard to other currently available vaccines and vaccine strategies in development. It is concluded that, encouragingly, DNA vaccines still offer significant potential, with more recent developments such as improved vectors and delivery systems likely to have an important impact; and in addition, the potential safety of DNA as a vaccine is becoming increasingly apparent. Strategies for oral delivery may be suitable for some applications, with all nonparenteral routes likely to require suitable carriers or adjuvants. The diversity of experimental data attests to the increasing interest in vaccination for the treatment and prevention of disease.