We analyzed the kinetics of hematological recovery after autologous bone marrow transplantation in 13 patients with acute nonlymphoid leukemias (ANLL). A comparison was made with 31 patients with non-Hodgkin's lymphoma (NHL) whose bone marrow was harvested and cryopreserved, either at diagnosis or after intensive chemotherapy. Hematological recovery of ANLL patients was similar to that of pretreated NHL patients and significantly slower than that of untreated NHL patients. We suggest that chemotherapy before harvest (more than the possible decreased stem cell marrow potentiality resulting from the underlying disease) appears to be the main factor responsible for delayed recovery after autologous bone marrow transplantation in ANLL.