Catalysts readily suffer from particle attrition in fluidized beds. In this article, a commercial fluid catalytic cracking catalyst was sieved into several particle-size intervals to investigate the size effect on particle attrition. It is shown that an exponential decay equation presents a suitable description of attrition and that catalyst attrition is dependent on particle size. Steady-state specific attrition rate decreases with increasing particle size; however, initial specific attrition rate and decay time parameter change irregularly. For comparison of attrition resistances, a long attrition test is required to reach steady-state attrition, and the steady-state specific attrition rate is recommended. It is seen that the smallest particle-size interval is the most seriously attrited, while the two largest particle-size intervals are the most attrition-resistant. Furthermore, weak interactions appear among attrition behaviors of different intervals, and a linear combination method is effective to combine all interval samples to predict the attrition of the original full-sized sample. (c) 2016 American Institute of Chemical Engineers AIChE J, 63: 914-920, 2017