Hyaluronic acids (HAs) are the most versatile fillers on the market. Since their approval in Canada in 1998 and the United States in 2003, applications for facial contouring have been varied, with predictable and outstanding results. Numerous publications support their safety, durability, longevity, and application to reconstructive and cosmetic procedures for both surgical and nonsurgical applications. The incidence of complications is low, and the treatment of complications is relatively straightforward with the use of hyaluronidase. This article discusses the uses of the HAs in general, with regard to the various particles sizes (Restylane, Restylane Fine Lines, Perlane, Juvederm 18, 24, 30), which are available in Canada and will be available in the United States in the fall of 2006.