Abstract: A tensioning device for a printing form on a jacket surface of a printing unit cylinder in a printing unit of a rotary printing machine, the printing unit cylinder being formed with a tensioning gap for receiving ends of the printing form therein, a tensioning shaft being received in a bore formed in the printing unit cylinder, the tensioning shaft being held under pretensioning by tensioning elements, includes fluid-loaded cylinders disposed on the tensioning shaft for respectively locking and unlocking a tensioning element on the tensioning shaft, and a separate actuating cylinder for setting an operating pressure of the fluid-loaded cylinders; a printing unit cylinder with the tensioning device; a printing unit with a printing unit cylinder; and a printing unit cylinder cooperating with a transfer cylinder.