A detailed assessment of the buttocks is necessary to have an excellent result. The different aesthetic unit of the buttocks as well as the surrounding aesthetic units are important in determining the final result, and also the areas that will require liposuction and augmentation with fat. An experienced surgeon who performs Brazilian buttock augmentation on a routine basis will understand that this procedure is not only a fat injection procedure but also fat removal procedure. Let us take a look at this diagram. There are five main aesthetic unit of the buttocks. We have the central part which is the one that is going to provide your projection, and the lateral part which is going to determine the shape of the buttocks. We discussed already the different shapes of the buttocks, including the A shape, hourglass shape, square, V shape, and round buttocks. We also have the sacral triangle of the buttocks which extends from the intergluteal fold all the way to the top of the buttocks on both sides. We have the inferior gluteal fold and also right at the most medial part of the buttocks, we have the ischial aesthetic unit. All of these areas need to be addressed when a Brazilian buttock augmentation is performed, but each one will require a different approach depending on the need to improve this area. For example, the sacral triangle, this area needs to be liposuctioned extremely aggressively since it creates and defines the top of the buttocks, creating a beautiful blend between the lower back and takeoff of the buttock. Many times, the lateral part needs to be liposuctioned, depending on the type of the buttocks that you have. Fat may also be injected depending if you need an hourglass shape or an A-shaped buttocks. In the projection of the buttocks, which is the central part, fat is injected in different areas, depending on the areas of deficiency that you might have. Many times, the inferior gluteal fold of the buttocks needs to be filled. I tend not to liposuction this area too much, only if there is some ptosis or sagging or a fat pocket that looks unnatural. Violating the inferior gluteal fold can cause significant problems with more sagginess of the buttocks and banana rolls after surgery. Finally, the ischial area. This area is a fat pad that is very thick with a lot of fibrous tissue. This area is extremely important because most patients have a deficiency in this area. Many times this area needs to be dissected bluntly to release the fascia that attaches to the bone, and then the area filled with fat to provide a very nice round buttocks in the most inferior medial part of the buttocks. Understanding the aesthetic units of the buttock is extremely important for a successful Brazilian buttock augmentation. This procedure is not just liposuctioning some areas and injecting fat randomly. It requires a systematic approach for a good result.