Efficient gene transfer into human hematopoietic stem cells (HSCs) is an important goal in the study of the hematopoietic system as well as for gene therapy of hematopoietic disorders. A Lentiviral vector based on the human immunodeficiency virus (HIV) was able to transduce human CD34(+) cells capable of stable, Long-term reconstitution of nonobese diabetic/severe combined immunodeficient (NOD/SCID) mice. High-efficiency transduction occurred in the absence of cytokine stimulation and resulted in transgene expression in multiple Lineages of human hematopoietic cells for up to 22 weeks after transplantation.