AbstractWe describe our experience in processing 40 bone marrow aspirates harvested for autotransplantation from patients with several hematological diseases using the CS‐3000 blood cell separator. The bone marrow of the first 30 patients was processed by a semiautomated method, and a fully automated procedure was used for the remaining 10 cases.Both procedures were developed in our laboratory and yielded a similar average mononuclear cell recovery of 87.78% and 86.98%, respectively, and similar nucleated cell recovery (27.39% and 27.11%). The cloning efficiency of hematopoietic progenitor cells, measured as the total CFU‐GM colony recovery in the in vitro cultures, did not differ between processed and recovered mononuclear cells. On the other hand, all the patients with transplants showed complete hematologic recovery, and the time to engraftment was similar to that described for other procedures. The automated procedure resulted in an average red cell removal of 97.81%, similar to the semiautomated procedure (94.19%), though with a narrower range (96.31–98.6% vs. 80.34–98.34%). The time taken to process a similar amount of bone marrow cell suspension was very different for each method: 1 hour for the fully automated vs. 2 1/2 hours for the semiautomated method to process 1.000 ml. Furthermore, the semiautomated procedure required the addition of homologous or irradiated plasma in a laminar air flow chamber, while the automated method is performed in a closed sterile system. We conclude that our procedure using the CS‐3000 processor is an efficient method for fully automated large‐scale processing of human bone marrow cells. © 1992 Wiley‐Liss, Inc.