A replication-defective retrovirus vector containing the human beta-globin gene and 36-base-pair HS2 enhancer (N2A beta E36) was constructed and transferred into psi-2 and PA317 packaging cell lines. Titers of amphotropic recombinant retrovirus ranged from 10(3) to 10(4) CFU/ml. Southern blot analysis indicated that intact human beta-globin gene was stably integrated into the genome of the target cells. Northern blot hybridization analysis showed that human beta-globin gene could be expressed in mouse fetal liver cells.