We have analysed seven polymorphic restriction sites of the human beta-globin gene cluster of six members of a Chinese family with a beta +-thalassemic sibling. The seven polymorphic sites analysed are the HincII site at the 5'-end of the epsilon-globin gene, the HindIII sites in the two gamma-globin genes, two HincII sites within and at the 3'-end of the psi beta 1 pseudogene, the AvaII site in the beta-globin gene and the BamHI site located at the 3' side of the beta-globin gene. The beta thal chromosome has been identified to have a haplotype of +----++ with respect to these seven polymorphic sites. This is also the most predominant haplotype associated with beta +-thalassemia in Mediterranean and Chinese populations (Chen et al., 1984; Orkin et al., 1982). Of the seven sites analysed in this family, four will be useful in prenatal diagnosis of beta-thalassemia in subsequent pregnancies in the family.