In a transdermal therapeutic system (TTS) comprises a matrix layer based on polyacrylate (I) and containing fentanyl as active agent (A), a backing layer impermeable to (I) and a protective layer to be removed before use, (I) is self-adhesive, is free of carboxy groups and has a saturation solubility for fentanyl of 3-20 wt. % and the (A)-containing layers have at least 80 wt. % of their (A) content in molecular dispersed solution form.