Autologous stem-cell transplantation is a common therapy for B-cell non-Hodgkin lymphoma. However, a concern with the procedure is the potential of malignant cells to reinfuse with the stem-cell graft. Thus attempts have been made to purge, or eliminate, malignant cells from the graft. The oldest, and most well studied, method for prevention of reinfusion is in vitro use of antibodies against B cells that bind or lyse malignant B cells and healthy cells, while leaving T cells and stem cells to be reinfused. In the past 5 years, investigators have used rituximab, an antibody against CD20, to purge malignant cells in vivo without any manipulation in vitro. Both conventional and new techniques have shown promise, but their exact role remains to be defined. We analysed data on the purging of B cells by use of antibodies in the setting of autologous transplantation, with emphasis on the emerging technique of in vivo purging.