A change in the recommendations for routine immunization of children is indicated because of the reduced risk of exposure to wild-type polio viruses and the continued occurrence of vaccine-associated paralytic poliomyelitis after oral polio vaccine (OPV). All children should receive four doses of vaccine before the child enters school. Regimens of sequential inactivated polio vaccine (IPV) and OPV, IPV only, or OPV only are acceptable. Each regimen has advantages and disadvantages. In special circumstances, one of the regimens is preferred or recommended. Because logistical problems with the current childhood immunization schedule may make these new recommendations difficult to implement immediately, their adoption likely will be gradual. Nevertheless, assuming continued progress toward global eradication and the development of new combination products, the routine use of an IPV-only regimen is likely to become desirable and feasible in future years.