No prospective randomized trials have evaluated the most efficacious dose of cyclophosphamide to mobilize autologous stem cells. We previously demonstrated that the time to collection of autologous hematopoietic stem cells is 10-12 days following the one dose of cyclophosphamide and daily G-CSF (granulocyte-colony stimulating factor).9 This prospective randomized trial is designed to determine if a lower dose of cyclophosphamide (1.5 gm/m2) will be as efficacious as the intermediate dose (3 gm/m2), based on cell number collected, number of apheresis required and resource utilization.