Prenatal diagnosis of beta-thalassaemia and sickle-cell anaemia was attempted in 24 pregnancies. Adequate amounts of fetal blood (for studying globin-chain synthesis) were obtained in 22 cases. 4 cases of homozygous beta-thalassaemia and 2 of sickle-cell anaemia were diagnosed. The difference between the homozygous and non-homozygous states was well defined. Fetal bleeding from cord puncture and amnionitis resulted in the loss of three fetuses, and methods to avoid these complications are being devised. It is concluded that prenatal diagnosis of disorders of beta-globin synthesis is feasible.