Hematopoietic reconstitution was assessed in 26 consecutive patients who underwent autologous bone marrow transplantation (ABMT) with ASTA-Z 7557 purged bone marrows. Of the 26, 17 had acute non-lymphoblastic leukemia (ANLL), 7 had acute lymphoblastic leukemia (ALL), 1 had non-Hodgkin's lymphoma (NHL) and 1 had multiple myeloma (MM). Twelve patients had practically no CFU-GM growth after ASTA-Z treatment. No statistical difference was observed in hematopoietic reconstitution between patients with or without in vitro CFU-GM colony growth. No significant linear correlation was observed between CFU-GM content in the treated graft and day of engraftment. In vitro CFU-GM growth has no predictive value in assessing hematopoietic recovery in vivo. Patients with no CFU-GM growth demonstrated normal engraftment.