Thus far, studies on the effects of the polydisperse size distribution on the minimum particle entrainment velocity (U-PU) in horizontal pneumatic transport are limited to binary mixtures of sandlike particles. Herein we experimentally investigate U-PU of ternary mixtures involving large (i.e., 400 and 170 mu m) and fine particles (40 mu m), where the roles of the fine particles in the entrainment of the large particles are elucidated. The presence of the 40 mu m particles below approximate to 20% (w/w) enhances the entrainment of the 400 and 170 mu m particles attributed to the high interstitial velocity of the conveying air because the fine particles occupy the interstitial spaces of the larger particles. Similar to monodisperse particles, a master curve of the particle Reynolds number versus Archimedes number is obtained for the ternary mixtures. From the master curve, a new empirical correlation for polydisperse U-PU is derived using the Sauter mean diameter, where improved U-PU predictions are demonstrated.