While individual immunoprophylaxis requires an effective vaccine, disease control requires an effective strategy for the application of the vaccine. In India, the oral polio vaccine (OPV) is given to children from 3 months to 2 years of age, in a 3-dose schedule. This strategy has not resulted in a fall in disease incidence in any community. It is suggested that two factors are responsible for the poor performance of OPV. First is a geographic variation in the response of infants to OPV, which result in only 80 per cent effective immunisation after 3 doses. The second factor is related to the age at which immunisation will achieve maximum benefit. Since the rate of natural poliovirus infection is highest during 6-18 months of age, immunisation should be completed by 6 months of age for disease control. If this is not feasible, an alternate strategy is necessary. It is suggested that pulse immunization in geographic units of population is a suitable method to control poliomyelitis.