The invention relates to a plate-type heat exchanger, in particular for motor vehicles, having a plurality of plate pairs for forming first, second and third flow paths, a spatial region for fourth flow paths being formed between adjacent plate pairs, the plate pairs being formed from at least one first plate and a second plate in order to form the first flow paths and the second flow paths between the first and second plates, the third flow paths also being formed between the first plate and the second plate or an attachment plate being placed upon the first and/or the second plate in order to form the third flow path between the first plate and the attachment plate and/or between the second plate and the attachment plate.