This report presents an account of fatal hemolytic disease of the newborn (HDN) due to anti-D in a mother whose red cells showed the phenotypic characteristics of Rh positive Du variant. The proposita's third pregnancy was uneventful until the eighth month, when she presented with an unusually large abdomen. A sonogram showed fetal hydrops, and amniocentesis yielded a delta OD450 reading in Zone 3. Anti-D with a titer of 4096 was identified in the mother's serum. Following delivery by cesarean section, the premature infant did not respond to resuscitation. The autopsy findings were consistent with Rh erythroblastosis fetalis. The proposita has been classified as a Category VI Du variant with anti-D in her serum.