For patients with end-stage organ disease transplantation of human organs is a well-established therapy, and in most cases it is the only life-saving one. But the lack of available organs is a big problem. The legal basis in Germany is the transplantation law (TPG). According to this law, every ventilated patient with diagnosed brain death is a potential organ donor. However, brain death may lead to strong reactions in the patient's cardiovascular system as well as disturbances in thermoregulation, water and electrolyte balance, and the endocrine and haemostatic systems. Thus, protecting the organs of the organ donor and, furthermore, caring for his or her relatives are great challenges for every physician and nurse in the intensive care unit.