Summary Examination of available statistics suggests that primary vaccination in the age-group 1–4 years and revaccination within ten year intervals is the most appropriate scheme of vaccination against smallpox to adopt when the incidence of, and mortality from complications are considered. Vaccination performed within ten years prior to an attack of smallpox will reduce the mortality, severity of attack, and scarring from the disease in most cases. For reasons outlined it is felt that routine vaccination of infants and periodic revaccination as stated is justifiable and should be continued.