Recombinant lentiviral vectors having a region encoding a functional .beta.-globin gene; and large portions of the .beta.-globin locus control regions which include DNase I hypersensitive sites HS2, HS3 and HS4 provides expression of .beta.-globin when introduced into a mammal, for example a human, in vivo. Optionally, the vector further includes a region encoding a dihydrofolate reductase. The vector may be used in treatment of hemoglobinopathies, including .beta.-thalessemia and sickle-cell disease. For example, hematopoietic progenitor or stem cells may be transformed ex vivo and then restored to the patient. Selection processes may be used to increase the percentage of transformed cells in the returned population. For example, a selection marker which makes transformed cells more drug resistant than un-transformed cells allows selection by treatment of the cells with the corresponding drug.