The number of stem cells in blood can be expanded. This expansion is often referred to as mobilization and may be achieved using chemotherapy, cytokines, or a combination of both of them. Stem cells obtained from the peripheral blood after mobilization regimen by apheresis, cryopreserved and stored in liquid nitrogen refrigerators. The mechanism of mobilization is multi-step process with a crosstalk between cytokines, adhesion molecules, and stromal cell-stem cell interaction. On the basis of understanding factors affecting mobilization, new approaches have been designed and are now starting to undergo clinical testing for both autologous and allogenic stem cell mobilization and transplantation.