Alan R. Spivack, MD, Assistant Professor of Clinical Medicine, Washington University School of Medicine; Associate Attending Physician, The Jewish Hospital of St Louis: A 49-year old man had a lifelong history of classic hemophilia with demonstrated factor VIII levels of 1% of normal. (Percentage of normal is determined by comparison of the patient's plasma clotting time to a curve calibrated from dilutions of known normal plasma using specific factor-deficient plasma as substrate.)1 The patient had multiple joint and soft tissue hemorrhages, both spontaneously and secondary to trauma, for which multiple transfusions of plasma and plasma components had been given. Hepatitis was diagnosed in 1964. In 1972, a pseudotumor of the thigh was surgically resected, resulting in a difficult postoperative course due to prolonged hemorrhage. In 1974, a gastrointestinal tract hemorrhage secondary to peptic ulcer disease was successfully treated with multiple blood and plasma transfusions. Further diagnostic studies during this