ABO incompatibility and glucose-6-phosphate dehydrogenase deficiency G6PD are common haematological problems affecting the newborn. The resulting haemolytic disease of foetus and newborn (HDFN) caused by either of these pathologies generally follows a benign course. It is typically characterized by mild jaundice without significant anaemia. ABO incompatibility alone as a cause of foetal hydrops is extremely rare. We report a case of a newborn baby girl with an anti-B isoimmunisation and G6PD deficiency manifesting with hydrops foetalis, anaemia and hyperbilirubinaemia, born to a mother with blood group O.