No specific studies have been performed to determine benefits of lubricants in size bath mixtures for air-jet-spun cotton (Gossypium hirsutum L.) yarns. This study focused on the effect of size concentration and lubrication on the characteristics and weaving performance of modern air-jet-spun cotton-polyester blend yarns in comparison with conventional ring-spun yarn. Two yarns were made using conventional ring spinning and air jet spinning. Yarns were sized with 50% polyvinyl alcohol and 50% cornstarch at 10% solids. Nine processing conditions were chosen; wax or liquid lubricant was applied in concentrations of 3.0 or 7.0 %. Lubricants were applied either at size bath or in after-waxing form. A control sample without lubricant also was used. Samples were tested for strength, elongation and abrasion resistance and statistically analyzed to determine performance differences. Lubricants in application schemes, which include traditional in-bath lubrication as well as after-drying applications, degenerated the original size film and yarn structure physical performances obtained in the absence of lubricants. Lubricants added after drying caused less degradation of size abrasion resistance than did those added in mixes. Addition of lubricant did not consistently reduce the coefficient of friction of sized yarns. Use of traditional fatty liquid or wax lubricants with film forming sizes reduces the breaking strength and abrasion resistance of sized air-jet-spun yarns in a manner similar to that observed in ring-spun yarns.