I think the most important issue to address in answering this question is what do we mean by "work." Sculptra, or L-polylactic acid, is an injectable filler that has been used for many years, mainly to add temporary volume to the face. Relatively recently we also discovered that volume can be produced with Sculptra in other areas of the body too, most notably the buttocks. We know that in this sense, that is in the production of volume in tissues, it works. The real question is will it work the way you want it to work. I have experience with injection of both fat and Sculpta in the buttocks, and there are some differences between them that are worth noting. None of these things are absolutely "good" or "bad" - in some cases what may be "good" may be undesireable in others. Thus, it is best to just be objective and recognize the more factual information about the treatments and then decide which one suits your needs best. Sculptra has the advantage of being available "off-the-shelf," meaning that we don't have to harvest it from somewhere else on your body, we can plan a treatment a little easier, and you won't have to heal or recover as long. This is particularly good for someone who wants some additional volume in the buttocks but doesn't have enough fat for a fat transfer procedure. On the other hand, Sculptra is not living tissue, and as such, the effects will be temporary, usually lasting a couple of years or so, depending upon how much was used. In general Sculptra is dosed by the number of vials injected, and while this will vary from person to person based upon size and amount of volume desired, the average person needs about 5 - 10 vials on each side of the buttocks, with 2 - 3 treatments required to attain the desired results. This can run into some cost limitations, as each vial of filler used will add to the cost. At the upper ends of numbers of vials used, the cost of the procedure can start to approximate the cost of a surgical fat transfer, or BBL (Brazilian Butt Lift) procedure. For this reason I generally see Sculptra more as a shaping and subtle volume corrector as opposed to a treatment to add significant amounts of volume. Done correctly, both procedures are very safe, but I would say that Sculptra carries a bit less risk than fat transfer simply because there are no issues with donor sites when using Sculptra, and the risk of injecting into blood vessels should be significantly less. The bottom line though is that Sculptra definitely works in the buttocks, and if expectations and goals are realistic, and the right patients are selected for the procedure, it can be very satisfying indeed. My best advice is to consult with board certified surgeons who offer both procedures so that you will get the best perspective and learn about all of your options. That way you can make an informed decisino and better select the procedure that is right for you. Best of luck.