During a recent study of a group of patients with hemolytic jaundice before, during and after splenectomy, we1have been disturbed on two occasions because of unfavorable reactions following transfusion of whole blood. A general review of the voluminous literature on hemolytic jaundice failed to reveal a single title referable to this complication, but submerged in the detailed study of case reports there are warnings of its occurrence and possibility. As a result of our experience, it seemed feasible to focus attention on the subject and to present the clinical manifestations and the possible cause. REPORT OF CASES Miss M. B., a housemaid, aged 25, entered the University Hospital for the third time Nov. 30, 1936, with symptoms of a severe crisis of hemolytic jaundice. On the two previous hospital admissions, four years before, she had been in similar crises with a red blood cell count of about one