A proposed hemopoietic stem cell gene therapy for treatment for HIV infection would involve transduction of CD34+ hemopoietic stem cells with vectors encoding anti-HIV constructs. Peripheral blood has proved to be a useful source of these hemopoietic stem cells and this study exploits this finding. Small quantities of peripheral blood were obtained from HIV-negative patients and HIV-positive patients who were and were not receiving hemopoietic growth factors (HGFs). CD34+ cells were obtained from these samples using a simple technique and scored for frequency of colony type. This demonstrated that HIV-negative patients had the highest frequency of colony-forming units (CFUs). HIV-positive patients not treated with HGFs had a lower frequency of CFUs, but the same colony type distribution as HIV-negative patients. HIV-positive patients treated with HGFs had the lowest frequency of CFUs, but their colony type distribution demonstrated that they had responded to treatment. CD34+ cells selected in this way were also transduced with the murine retroviral MFG vector using a technique that demonstrated transduction efficiencies ranging from 2% to 16% (median, 11.5%). This study simplifies the experimental requirements for development of a hemopoietic stem cell gene therapy for HIV infection and offers the possibility that longitudinal studies could be performed on peripheral blood CD34+ cells from HIV-positive or HIV-negative patients without the need for granulocyte colony-stimulating factor mobilization.