The invention relates to a plate heat exchanger comprising a plurality of plates having flow channels, wherein a first plate has a front side having at least one flow channel for a first fluid and a second plate has a front side having at least one flow channel for a second fluid, and wherein the plates have through openings via which the flow channels for the same fluid are respectively connected to one another, wherein a front plate, which is placed in front of the front side of the first plate, has ports for the first fluid and for the second fluid, wherein an end plate forms the end of the aligned plates, wherein the plates and ports are formed from plastic, and wherein the plates are bonded or welded tightly together.