The gradually evolving technology for vaccine development from Jenner to recombinant genetics has provided both solid accomplishment and possible bases for prophylactic control of essentially all the infectious diseases of humans. The present review gives a prospective view of future vaccines and the new biotechnology as illustrated mainly in the examples of vaccines for control of hepatitis and of herpesvirus infections. Although vaccines offer great benefit for human health, their use is restricted in developing countries by lack of funds and in developed countries such as the United States by failure of application, mainly in adults. Practical matters relating to vaccine use must be resolved if there is to be justification for vaccine development.