The invention relates to a transdermal therapeutic system (TTS), comprising a backing layer, which is permeable to the active ingredient, at least one matrix layer, comprising fentanyl or an active agent analogous to fentanyl, based on polyacrylate and a protective layer to be removed before usage, characterized in that the polyacrylate polymer is self-adhesive, free of carboxyl groups, has a saturation solubility for fentanyl of 3 to 20 wt. %, preferably of 4 to 12 and particularly of 5 to 10 wt. % and the layers contain at least 80% of the included active ingredient in a molecularly-dispersed, dissolved form.