Schematic representations of hematopoietic development from in vivo and in vitro models. Both human and mouse in vitro models have been established for hematopoietic differentiation in a defined culture system from embryonic stem (ES) and adult cell-derived induced pluripotent stem (iPS) cells. For the in vivo model, the mouse inner cell mass undergoes differentiation, later forming the yolk sac, which generates mesodermal cells and induces hematopoietic stem cells (HSCs), hematopoietic progenitor cells (HPCs) and mature hematopoietic cells (HCs). Successfully generated HSCs from both in vitro and in vivo models might be applied to HSC transplantation for hematopoietic disorders. Further differentiation of HSC in a cytokine-defined culture system produces hematopoietic cells for hematopoietic cell transfusion. Thorough understanding of molecular mechanism on these models will be beneficial for both drug screening as well as the mechanism of hematopoiesis development.