Approx. 40 HIV treatment sites in Germany are planned to be involved in the documentation. The recruitment target is to include a total of 400 patients in the study across Germany. In order to allow for adequately answering in particular the problems regarding HLA-B*5701 testing, at least half of the recruited population should not have received abacavir (ABC) in their prior therapy. Each site will be allowed to recruit a maximum of 5 patients per month and a maximum of 20 patients in total. If the monthly quota of 5 patients is not utilized, the difference may be transferred to the subsequent months.