Abstract TRANSDERMAL THERAPEUTIC SYSTEM FOR ADMINISTERING THE ACTIVE SUBSTANCE BUPRENORPHINE The invention relates to a transdermal therapeutic system for administering the active substance buprenorphine. Said system comprises at least one carboxylic acid that determines the solubility of buprenorphine in the matrix layer and that can likewise be absorbed. The transdermal therapeutic system according to the invention is used in the treatment of pain and is characterized by a considerab/y increased utilization of the active substance.