A Chinese family in which two siblings suffer from haemogloblin (Hb) H disease due to (--SEA) alpha-globin gene deletion and alpha2-codon 30 (DeltaGAG) mutation is described. Both siblings are transfusion-independent and have survived to adulthood. In contrast to previous report of hydrops fetalis associated with zeta-alpha-thal-1 and alpha2-codon 30 (DeltaGAG) mutation, the zeta-globin genes are intact in the two siblings, which most probably alleviates the gamma-chain excess and protects the fetus from severe anaemia. Correlation of genotype with phenotype in Hb H disease is important for genetic counselling, especially in the antenatal setting.