Ultrasonic vibrations have various kinds of applications in machining operations. A large number of researchers have been involved in the investigation of ultrasonic effects in conventional machining operations. In most of the cases, they have obtained favorable effects. In this regard, this paper discusses the effects of ultrasonic vibrations, especially in EDM processes. The mechanisms which are helpful in improving the material removal include, cavitation, micro-streaming and impact forces by ultrasonic waves. One of the major challenges in EDM is to improve the sparking and flushing efficiency, which is critical in processes such as micro-EDM. Generally, it is understood that ultrasonic vibrations reduce thermal damage of the surfaces generated in EDM. Two ultrasonic parameters influencing the processes are ultrasonic amplitude and frequency of ultrasonic vibration. Several researchers have done mathematical modeling of the effects of ultrasonic vibrations in EDM. It helps in the prediction of key factors influencing the process, such as ultrasonic force required for debris evacuation and debris concentration at the inter-electrode gap.