Abstract: A coupling for coupling together hoses or pipes for a pressure medium is described. The coupling has a coupling sleeve and a nipple insertable in the sleeve. The coupling sleeve has a valve device for opening the flow-through of the pressure medium as the nipple is inserted to its engagement position and consists of a sleeve-shaped front part and a sleeve shaped rear part. The front part is rotatable but axially essentially non-displaceable and joined to the rear part by means of a resilient lock ring. The valve device also has a valve body in the form of a sleeve, a valve seat for cooperation with the valve body and a blocking sleeve for cooperation with the nipple upon insertion thereof.