Abstract: A heat exchanger, particularly a refrigerant evaporator, is disclosed which comprises a soldered block of stamped plates which, in pairs, form a U-shaped guide and collecting ducts for a heat exchange medium. Corrugated ribs are arranged between the plate pairs, and plate-shaped lateral parts are arranged on the front ends of the block with the insertion of corrugated ribs. It is provided that, in the area of the collecting ducts, the lateral parts are provided with at least one profiling which, together with a covering sheet closing off the last plate, forms a chamber which has a connection to at least one of the collecting ducts.