The proliferation and expansion of umbilical cord blood human hematopoietic stem cells (HSC) in ex vivo culture was examined with the goal of generating a suitable clinical protocol for expanding HSC for patient transplantation. Expansion with three different cytokine combination after different intervals of freezing was done. Expansion was assessed by flow cytometry. Umbilical cord blood human hematopoeitic stem cells (HSC) can be expanded in vitro but additional studies are needed to establish their functional activity.