Autologous stem cell transplantation has been shown effective in the long-term control of follicular lymphoma. Lymphoma, however, can progress after high-dose treatments. Lymphoma cells have been proved to contaminate bone marrow and peripheral blood stem cells (PBSC) collections and may contribute to relapse after autotransplant. The presence in peripheral blood and marrow of PCR-detectable cells bearing the bcl-2 rearrangement appeared to be a surrogate marker of disease and the achievement of a bcl-2 negative status is associated with a lower risk of recurrence. Several methods have been attempted to abolish graft contamination: in vitro treatment with cytotoxic agents, in vitro treatment with anti-B-cell monoclonal antibodies and complement, immunomagnetic beads, positive selection of CD34+ cells. All these techniques usually produce loss of cells, are time-consuming and expensive, and neoplastic depletion is often partial with residual polymerase chain reaction (PCR)-positive cells in the graft.