The problem of quality and quality assurance for the free exchange of blood and blood products in Europe is discussed. The background of all discussion of quality is the categorical theory of Aristoteles. The philosophical basis is described. The fundamental law of the daily work of a blood center has to be a philosophy of quality which depends on the sociodemographic situation in the region. This basic varies from country to country in Europe. The importance of the supranational bodies in Europe is mentioned. The weightness of the Code of Ethics is discussed. Virus safety, purity and validity of blood and blood products are described as parameters of the quality aspects. Finally it is confirmed that a well running blood program is a multicategorical problem.