A recent randomized multicentric French study has shown that intensification with stem cell rescue improves the response rate and progression-free survival in multiple myeloma. Transplantation with primed peripheral blood stem cells (PBSC) displays a faster hematological recovery, especially for platelets, as compared with a bone marrow stem cell graft. In multiple myeloma, the optimal mobilization method for PBSC is unknown. The present study compares mobilization with cyclophosphamide 4 g/m2 + G-CSF 5 micrograms/kg versus G-CSF 5 micrograms/kg alone versus G-CSF 10 micrograms/kg alone in two cases of multiple myeloma, using an intrapatient controlled evaluation of the amount of CD34-positive cells obtained during each leukapheresis. In both cases, the highest CD34-positive cells yield was obtained with G-CSF at 10 micrograms/kg. Despite the low number of cases, this method, devoid of life-threatening toxicity, might be of greatest interest in multiple myeloma.