Abstract: A heat exchanger for a refrigeration circuit includes a plurality of fluid tubes aligned in a parallel relationship with each other and corrugated fins disposed therebetween. A pair of header portions are connected with the ends of the fluid tubes. The header portions includes plate members which have a plurality of elongated holes for receiving the ends of the fluid tubes therein. Cup-shaped members are disposed in sealing contact with end surfaces of the plate members to cover the ends of the fluid tubes. With this construction, the refrigerant passageways can be securely maintained. Further, the core of a heat exchanger can be shaped to conform to the space available for mounting the heat exchanger, to thereby enhance the efficiency of the heat exchanger.