Abstract: A heat exchanger and blood oxgenator apparatus includes a housing having a blood inlet portion, a blood outlet portion, and a housing wall defining an enclosed chamber disposed along a chamber axis between the blood input portion and the blood output portion through which to pass a quantity of blood to be temperature controlled. A heat exchanger tube having an exterior surface and a hollow interior through which to pass a heat exchange medium for purposes of exchanging heat with a quantity of blood brought into contact with the exterior surface, is disposed in a generally helical coil that is mounted within the chamber to encircle the chamber axis. A scalloped inner surface is included on the housing wall to face generally inward toward the heat exchanger tube.