The rapid rescue of hematopoiesis following transplantation of peripheral blood stem cells (PBSC) has facilitated expanded application of high-dose chemotherapy regimens for several malignancies. A variety of regimens have been described to enhance the circulation of PBSC, including the use of hematopoietic growth factors, either alone or following myelosuppressive chemotherapy. Such improvements of PBSC mobilization can increase the number of hematopoietic progenitors for transplantation and reduce the number of leukapheresis procedures required. We review several approaches to the collection of PBSC, including our experience with the use of cytokines in addition to chemotherapy. In addition, we discuss the investigation of novel cytokine combinations and in vitro expansion techniques, which may lead to further improvements in both the efficiency of PBSC collection and hematopoietic recovery following transplantation.