It is not possible to examine all the innovations relating to the generation of high-power sound waves using composite materials, because of the multitude of applications (sonar, welding, cleaning, sonochemistry, etc.) and the extremely wide range of frequencies used (50 kHz–10 MHz). In this chapter, we will focus on the medical field. Nonetheless, a large number of problems or concepts raised here can be extended and adapted to industrial or military applications. After demonstrating the advantages that the composite material provides for the design of ultrasonic sources, we will examine the specific problems linked to continuous and pulsed ultrasound sources.