Pilling of fabrics that are a blend of polyester and cotton negatively affects hand and appearance. The dynamic equilibrium between two opposing effects, pill formation and pill wear-off, is responsible for the number of pills. Several polyester fiber properties affect pill fromation and wear-off. The use of high-strength, low-denier polyester has contributed significantly to the problem. Pill resistance also depends on the type of yarn spinning system. Even when optimal fiber properties are determined, fabric constructed with air jet spun yarn is the most pill resistant, and fabric constructed with rotor spun yarn is the least pill resistant. Pilling properties of both knit and woven fabrics are evaluated and compared. 9 refs.