Optical films, and organic light-emitting display devices employing the same, include a high refractive index pattern layer including a lens pattern region and a non-pattern region alternately formed, wherein the lens pattern region includes a plurality of grooves each having a depth larger than a width thereof, and the non-pattern region has no pattern; and a low refractive index pattern layer formed of a material having a refractive index smaller than a refractive index of the high refractive index pattern layer, wherein the low refractive index pattern includes a plurality of filling portions filling the plurality of grooves.