Quality and quantity of mobilized peripheral blood stem cells determine the safety of tandem autologous transplants in myeloma. Using the same mobilization chemotherapy with DT-PACE in two consecutive protocols, robustness of stem cell collection and rapidity of engraftment after transplantation were assessed. We employed either twice a day filgrastim versus two doses of pegfilgrastim. Advantages of pegfilgrastim were: (i) a higher percentage of patients collected 15x10(6)/kg in the first three days (p<0.001); (ii) the median number of CD34 cells/kg collected on day 1 was higher (p=0.004); (iii) the median number of growth factor injections was 2 versus 26 (p<0.0001); (iv) post-transplantation neutrophil recovery was faster after first and second transplant (p<0.001) and (v) platelet recovery was faster after first transplant (when less stem cells were infused) (p=0.01). Pegfilgrastim may be considered the standard of care for stem cell mobilization.