Ultrasonic machining (USM) is a nontraditional mechanical machining process and can be used in many applications. This chapter presents USM and rotary ultrasonic machining (RUM), including definitions, machine elements, input variables and their effects, applications, and advantages and disadvantages. In addition, ultrasonic vibration-assisted (UV-A) machining processes will also be introduced. These processes include UV-A turning, UV-A drilling, UV-A milling, UV-A grinding, UV-A electrical discharged machining (EDM), and UV-A laser beam machining (LBM). The machining principles, input variables, and major features for each process will be discussed.