SummaryThe autor reviews classification of familial erythroblastosis and puts forward a pathogenic interpretation of hemolytic phenomenons in the fœtus and the new born, according to conceptions initiated by Wiener, Landsteiner and Peeters (1940).Symptomatology of the commonest form (fœtal and placentalœdema) is illustrated by a typical case of hemolytic accidents in a syphilitic new born: Rh factor or A and B antigens cannot be incriminated since both mother and child were Rh–and of the same blood-group (O). Discussion stresses complexity of study of agglutination and hemolytic manifestations in such cases.