In the five-year period, 1959-1963, 209 patients were given massive blood transfusions of at least 5,000 ml within a 24-hour period. The overall mortality was 45% and increased with the amount of blood given, the age of the patient, complicating medical conditions, and shock. When shock was prevented or quickly corrected, the mortality was 7%; however, when prolonged shock occurred in patients with preexisting or associated disease, the mortality was 93%. A serious bleeding diathesis occurred in seven patients. The incidence of wound complications in these patients was about four times that of the general surgical population for the hospital. One case of homologous serum jaundice occurred in a survivor.