The molecular defect in two unique cases of Hb H hydrops fetalis has been characterized. Both cases are due to co‐inheritance of a ‘non‐deletion’ defect affecting the α2 gene: at codon 30 (ΔGAG, Glu) and codon 59 (G → A, Gly → Asp) respectively, and a ζ‐α thalassaemia (thal) 1 or α thal 1 genotype. These two non‐deletion defects, unlike previously described cases, resulted in severe anaemia of the fetuses and emphasize the importance of performing prenatal diagnosis for these families.