Rh antibodies were found in the breast milk of 2 mothers with erythroblastotic children. The Rh antibody titer was much higher in both instances than in the case reported previously. In the first case, the Rh antibody titer of the serum was 1:256 while the milk specimen obtained on the fifth day following delivery showed an antibody titer of 1:16. In the second case, the Rh antibody titer of the serum was not higher than 1:8 and the colostrum, upon examination, revealed the same titer. Those findings suggest that the content of Rh antibodies in breast milk is relatively high in the first days following delivery, especially in the colostrum. In the few cases we examined, we have not been able to demonstrate antibodies in the breast milk unless they were present in the serum. Assuming that Rh antibodies in the breast milk pass through the intestinal canal and enter the circulation, breast milk might be the cause of further damage to blood cells of erythroblastotic children.