We describe a case of congenital dyserythropoietic anaemia (CDA) presenting at week 20 of pregnancy with hydrops fetalis and very severe anaemia. Fetal blood examination showed marked erythroblastosis with morphologic alterations while the basic haematological and biochemical tests were in the normal range. The fetus received intravascular red blood cells transfusion at 20 and 25 weeks of gestation. After a caesarean section at week 33 the child became transfusion dependent. Haematological investigations demonstrated that the child is affected by a CDA-like picture which, although morphologically similar to CDA II, is Ham test negative and does not show the typical membrane proteins alterations.