Attrition resistance is a key design parameter for catalysts used in slurry phase Fischer-Tropsch (F-T) reactors, especially for industrial-scale reaction. It is well-known that iron F-T catalyst particles undergo physical attrition and chemical stresses caused by phase transformations. Here we report on attrition properties of a Fe-Cu-K-SiO2 catalyst used in a pilot-scale stirred tank slurry reactor (STSR) under low temperature F-T reaction conditions. The wax-free catalysts were characterized by SEM, EDS, BET surface area measurements, and a Mastersizer 2000 for particle size analysis. The results show that, after 408 h of reaction in an STSR, the particle size reduction due to erosion/abrasion and fracture was apparent. Large reductions in the Sauter mean diameter (93.45%) and the volume moment diameter (71.67%) were observed. The increase in the fractions of particles smaller than 5 and 10 mu m was 18.25 and 30.11%, respectively. We concluded therefore that the catalyst underwent more severe attrition in industrial application and the attrition was mainly caused by the fracture of larger or smaller particles. Further study is needed to improve the catalyst attrition resistance.