[Old and new dangers of blood transfusion (author's transl)].

The predominant danger of blood transfusion, even after the discovery of the ABO and Rh systems, is the immunological risk. This led in 1940 to a regulation of blood transfusion in Germany by official guidelines which were constantly adjusted in the light of new research results. The dangers due to deterioration on storage still receive too little attention although these may be of greater danger to the patient than immunisation risk. Also the assessment of other medical problems of transfusion is insufficiently applied to clinical routine.