We have performed sequential studies examining the modification of hematopoietic toxicity after the administration of high-dose cyclophosphamide, etoposide, and cisplatin (CVP). The sequential studies include a comparison of the influence of autologous bone marrow transplantation (ABMT) on hematopoietic recovery after CVP, with or without growth factors. These studies demonstrate a significant shortening of the duration of neutropenia with ABMT, but minimal impact on the number of infectious episodes, when compared to those not receiving ABMT. The addition of mobilized peripheral blood stem cells (PBSC) to ABMT followed by growth factor was found to enhance platelet recovery, but did not significantly further reduce the period of absolute neutropenia. Subsequent studies show that similar early hematopoietic recovery can be achieved by use of peripheral blood stem cells alone, pheresed following several days of subcutaneous administration of recombinant growth factors, but neutrophil recovery is more rapid with use of growth factor after PBSC infusion. Using the product of two phereses for each cycle of recovery appears to result in similar rates of hematopoietic engraftment after each cycle of CVP. In conclusion, the use of peripheral blood stem cells alone following sequential high dose CVP is associated with rapid neutrophil and platelet recovery. Caution should be exercised when using PBSC alone after high dose therapy, due to the lack of platelet recovery in some instances, which can be overcome by reinfusion of backup marrow. Thus, studies evaluating the role of PBSC after high dose therapy should continue.