Among the questions studied were: Was it possible to identify distinctive attributes of the patients who, though operated, did not require a transfusion or who required a large volume of blood? Were transfusions of non-red cell components related to use of red cells? Could transfusion frequency diagnosis for all blood products be used as a measure of transfusion practice? Did longitudinal comparisons of transfusions over the 9-year interval, 1980-1989, reveal significant trends? Was it possible to discriminate quantitatively between transfusion practices in different hospitals or set of hospitals, or at different times? What was the effect of autologous blood programs in transfusion practice? What was the contribution of comorbid conditions on red cell and component transfusion patterns.?