Twenty bone marrow aspirates harvested for autotransplantation from 20 patients suffering from several oncohematological diseases were processed using the automated Du Pont SteriCell processor. In 15 bone marrow harvests, the interface buffy coat cells were collected using the SteriCell processor in manual mode with a semiautomated procedure. The procedure yielded an average red cell removal of 84% and an average mononuclear cell (MNC) recovery of 86%. Cloning efficiencies of hematopoietic progenitor cells (CFU-GM and BFU-e) did not differ between processed and recovered MNCs. Four cryopreserved bone marrow buffy coats were thawed and reinfused into four patients who had undergone high dose chemotherapy. Stable engraftment was observed in all cases. In five bone marrow harvests, the SteriCell automated density gradient MNC isolation procedure was performed after buffy coat collection. The whole two-step procedure allowed an average MNC recovery of 69%. CFU-GM and BFU-e assays did not show a significant difference in cloning efficiency between processed and recovered bone marrow MNCs. We conclude that the SteriCell processor offers rapid, safe and feasible procedures for the semiautomated processing of human bone marrow for transplantation. The clinical efficacy of density gradient separated bone marrow employing the automated step and the opportunity to use fully automated processing must be investigated.