[Perinatal hemolytic disease due to incompatibility in the U system (author's transl)].

We report the case of a 3 week-old black infant who presented with hemolytic anemia due to an incompatibility with his mother in the U blood group system. Jaundice, present on the 3rd day of life, was considered as physiologic jaundice. A positive Coombs test led to the discovery in the mother's serum of an immune antibody against the U public antigen.