[Blood group compatibility testing for blood transfusions].

Acute and chronic dangers of blood-transfusion are listed. Three serologic demands in selecting donorblood are identity in the ABO-system compatibility in the Rh-system and a negative cross-match in the mode of a three-step Coombs-test. The often claimed consideration of the Kell-system is shown to be numerical in the background of transfusion-practice. The highest responsibility is taken by the physician in transfusing patients with Coombs-positive auto-immune-diseases in which the cross-match is positive and so present antibodies could be hidden.