In the twenty-first century, hyaluronic acid fillers, along with Botox, are recognized as the most ideal facial esthetic filler and are widely used by authors for penis augmentation. Therefore, in this chapter, we will examine the development process and characteristics of hyaluronic acid fillers and the current status of the global market. In addition, we would like to learn about products that have been approved by the FDA since Restylane, which was first developed in 1996, and introduce the characteristics and penis enlargement effects of KFDA-approved fillers for penis augmentation.