With the advent of modern surgical technique, the liberal use of whole blood transfusions has became widespread and so a variety of untoward reactions have been recognized. The complication of blood transfusions have been studied intensively during past 10 years, 1965~1974, in the Ewha Womans University Hospital. It has performed 3,589 cases of blood transfusions of at least 500cc during operation out of 10, 730 cases operation experiences. 184 cases among them were given massive blood transfusions of at least 2,000cc within about 3 hours period at operating room. The overall mortality was 9,8% and increased with the amount of blood given, the age of patient, complicating medical conditions, anatomical site of trauma, shock and operation time. When shock was prevented or quickly corrected, the mortality was decreased. However, when prolonged shock occurred in patients with preexisting or associated disease, the mortality was increased. The complications of transfusion were generally urtiearia (61%), high fever (15g) shock(12%), and wound infections (2%). The causes of death following transfusion may depend upon the complications of transfusion.