The invention relates to a dialysis device comprising an extracorporeal blood system, a dialysis fluid system, a dialyser and a control unit, wherein the dialysis device has a heating mechanism for heating the blood in the extracorporeal blood system before entering into the dialyser or in the dialyser, and a cooling mechanism for cooling the blood in the extracorporeal blood system after leaving the dialyser, and wherein the control unit is designed such that the blood is heated to a dialysis temperature before entering the dialyser or in the dialyser, which temperature is above the body temperature of the patient, and is cooled again to body temperature of the patient after leaving the dialyser.