Data from 16,320 deliveries from two time periods were examined to compare the incidence of positive direct Coombs' tests and the number of exchange transfusions performed, using different methods of screening and treatment in each time period. Early routine screening revealed an eightfold increase in the number of Coombs-positive infants, while the combined effect of instituting early screening and the change from white light to special blue light phototherapy greatly diminihsed the number of exchange transfusions. In addition, data concerning racial and blood antigen factors in ABO hemolytic disease of the newborn (HDN) are compared, showing an increase in incidence but no increase in severity for black infants and infants with blood type B. Also, use of cord blood parameters in management of ABO HDN is discussed.