Objective:To investigate the influence of GST-π gene transfer into human cord blood hematopoietic stem cells on their drug resistance against anti-tumor drugs in vivo.Methods:GST-π gene transfection into human cord blood CD34+ cells was carried out using a retrovirus vector PLJ-GST-π with the aid of fibronectin.Successful gene transfer was confirmed by in vitro colony assay and RT-PCR.GST-π gene transduced human cord blood CD34+ cells were then engrafted into 4-week-old total body irradiated NOD/Scid mice and carboplatin was intraperitoneally administered sequentially at 4 weeks interval 4 weeks after engraftment.Results:Peripheral blood(PB) WBC was significantly higher in GST-π mice than control mice after 2 course of carboplatin.Retroviral GST-π expression in bone marrow hematopoietic progenitor cells of recipient mice was detected by RT-PCR 16 weeks after Xenotransplantation.Conclusion:The transfection of GST-π gene could confer,to some extent,resistance to cord blood stem cells against carboplatin in vivo.