Background: The GlaxoSmithKline, oral live-attenuated human rotavirus vaccine RIX4414 Rotarix™) was shown to be highly immunogenic. A phase III, randomized, double-blind, placebo-controlled study(NCT00139347-e-Track444563) was conducted in Latin America to assess the effect of Rotarix™ on the immunogenicity of co-administered oral polio vaccine(OPV). Methods: 6568 healthy infants aged 6–12 weeks were enrolled to receive two doses of RIX4414 (RIX4414-OPV group:N = 4376) or placebo (Placebo-OPV:N = 2192) according to a 0,1–2 month schedule, administered concomitantly with Dose1 and Dose2 of routine vaccines including oral poliovirus vaccines (OPV), according to recommended local national immunization guidelines. For the immunogenicity subset for OPV (N = 900) seroprotection rates for anti-polio types1,2,3 antibodies were determined at 1 month post-Dose3 of routine pediatric vaccination(virus neutralization assay, cut-off≥8ED50). Of these, a subset of infants received an additional OPV dose at birth. Results: No significant difference in anti-polio1,2,3 seroprotection rates was observed at 1 month post-Dose3 of OPV between RIX4414-OPV and Placebo-OPV groups. Conclusions: Co-administration of Rotarix™ with OPV does not interfere with the immune response to OPV. This is of importance in considering the inclusion of RV vaccination into UMV programs in countries where OPV is still used.