A plate heat exchanger may include a plurality of stacked plates, each formed of flat troughs fitted into each other having substantially flat bottoms and connected at respective trough edges. The plurality of plates may separate first and second chambers from one another which are arranged alternately succeeding within the plate stack formed by the troughs. A first fluid may flow in parallel through the first chambers connected in parallel via associated openings in the plates, and a second fluid flow may flow in parallel through the second chambers connected in parallel via associated second openings. The plate heat exchanger may include a base plate for holding an end face of the plate stack. The base plate may be arranged on the end face of the plate stack, the end face formed by a convex side of a plate. The plate heat exchanger may include a flange.