Mucosal immunity is considered to be an important barrier for inhibiting person-to-person transmission of naturally occurring (wild type) poliovirus infection. This review briefly summarizes the results of a previously published study in which 79 oral poliovirus vaccine (OPV) vaccinated children and 93 enhanced-potency inactivated poliovirus vaccine (IPV) children were challenged with one of two doses of type 1 OPV virus to test the oropharyngeal and gastrointestinal mucosal immunity conferred by each type of poliovirus vaccine. Although both OPV and IPV produced excellent oropharyngeal immunity, OPV was clearly superior in decreasing fecal shedding of the challenge virus.