In a device for handling blood in extracorporeal blood circulation that has at least one oxygenator, one heat exchanger, and one blood filter, the inlets and outlets in the oxygenator/heat exchanger unit are embodied such that a blood flow cross section of A≧80 mm2, preferably A≧120 mm2, is assured. The device can also be operated in an isolated form as a single structural part, which takes on the functions of an oxygenator and a heat exchanger with a blood filter. If a pump is provided in the device, then the pump drive can be removed as needed.