We report 13 multiple myeloma (MM) or lymphoma patients who were failing PBSC mobilization after disease-specific chemotherapy and granulocyte-CSF (G-CSF), and received plerixafor to successfully collect PBSCs. Patients were considered poor mobilizers when the concentration of PB CD34+ cells was always lower than 10 cells/μL, during the recovery phase after chemotherapy and/or were predicted to have inadequate PBSC collection to proceed to autologous transplantation. Plerixafor (0.24 mg/kg) was administered subcutaneously for up to three consecutive days, while continuing G-CSF, 10–11 h before the planned leukapheresis. Plerixafor administration was safe and no significant adverse events were recorded. We observed a 4.7 median fold-increase in the number of circulating CD34+ cells after plerixafor as compared with baseline CD34+ cell concentration (from a median of 6.2 (range 1–12) to 21.5 (range 9–88) cells/μL). All patients collected> 2× 10 6 CD34+ cells/kg in 1–3 leukaphereses. In all, 5/13 patients have already undergone autograft with plerixafor-mobilized PBSCs, showing a rapid and durable hematological recovery. Our results suggest that the pre-emptive addition of plerixafor to G-CSF after chemotherapy is safe and may allow the rescue of lymphoma and MM patients, who need autologous transplantation but are failing PBSC mobilization.