Live attenuated influenza vaccine (LAIV) provides a useful tool to rapidly immunize populations in the developing world to prevent influenza outbreaks. In this noninferiority trial conducted in Asia and South America, where oral poliovirus vaccine (OPV) is still used, 2503 children aged 6 to <36 months with three polio immunizations were randomized to receive LAIV + OPV, placebo + OPV, or LAIV only. Immune responses in children receiving concomitant LAIV + OPV were noninferior to those observed in recipients of either vaccine alone. Response rates for different poliovirus types were similar in recipients of LAIV + OPV and placebo + OPV. Response rates to all influenza strains were similar in LAIV + OPV and LAIV-only recipients. Concomitant OPV and LAIV were safely administered to young children.