Abstract: The invention relates to a heat exchanger, particularly for motor vehicles, including at least one water tank disposed at one end of a bank (6) of tubes (8) with fines (7) through which a first fluid flows and a shell (2), such as a casing (9), defined by walls (12, 13, 14, 15) surrounding said bank and through which a second fluid flows. In this exchanger, two sides of the bank are adjacent to walls (12, 13, 14, 15) of the casing (9) braced against one another by assembly means positioning the bank (6) and supported by it. This exchanger is characterized in that the assembly means comprise mutual sliding engagement means (21, 23, 25, 26, 34) supported respectively in part by the bank (6) and by at least one of the walls (12, 13, 14, 15) of the casing (9). The invention relates in particular to motor vehicles.