In ultrasonic machining (USM), the material is removed primarily by repeated impact of the abrasive particles, and the material removal rate (MRR) and surface integrity are influenced by various factors including the material parameters of the workpiece materials. In this study, effect of the properties and microstructure of the workpiece materials on the MRR in ultrasonic machining of alumina-based ceramic composites was investigated. The distributions of strength of the ultrasonic machined specimens were used to evaluate the surface integrity. Results showed that fracture toughness of the ceramic composite played an important role with respect to MRR. In USM of whisker-reinforced alumina composites, the MRR depended on the whisker orientation. Studies of strength distributions of alumina-based ceramic composites machined by USMdemonstrated that the flexural strength varied narrowly from the mean value, and the composites with high fracture toughness showed higher Weibull modulus.