All Rh antigens should be considered to have the potential to cause hemolytic transfusion reactions and hemolytic disease in neonates. Anti-c is the most clinically important Rh antibody after anti-D. Anti C,E and e rarely cause hemolytic disease in newborns, whereas Anti-c causes severe neonatal hemolytic disease. Antibodies to the Kell system should be considered to have clinically relevant potential. They can cause hemolytic transfusion reactions and hemolytic disease in newborns.