THE DISCOVERY by Levine1 of the immunologic relationship between the Rh factor in the erythrocytes of the fetus and the formation of anti-Rh antibodies in the Rh-negative mother has been of the greatest importance in the understanding of that group of familial conditions in the newborn characterized by destruction of the red cells. On the basis of this explanation, however, certain assumptions arrived at by inference rather than by critical analysis of clinical studies have been made by many concurring writers. It is assumed, for instance, that hemolysis and agglutination produced by antibodies transferred from the mother to the fetus by way of the placenta are responsible for all ensuing organic damage, either through anoxemia due to anemia or through the overproduction of the products of erythrocyte destruction. Injury to the liver, when mentioned at all, is not considered as a primary pathologic process but is presumed to be