The feasibility of marrow cryopreservation for autologous bone marrow transplantation after 7 d in liquid culture was assessed in 10 leukaemic patients. A median of 0.17 x 10(8) nucleated cells/kg and 0.4 x 10(4) CFU-GM/kg could be collected after the complete procedure, with overall a consistent cell loss. Long-term cultures could be established from these cultured and frozen marrows, showing the persistance of precursors of haematopoietic and stromal cells. In vitro a significant decrease in the proportion of leukaemic cells could be observed in only one out of nine evaluable patients. This patient, with refractory AML, received an autologous transplant and is alive in continuous complete remission after 600 d. One patient with chronic myeloid leukaemia in acute phase underwent an autologous BMT with a marrow collected and cultured while in chronic phase and failed to engraft. These results show the feasibility of cryopreservation of cultured marrow cells for autologous bone marrow transplantation. The procedure is associated with poor cell recovery and must be improved to have a more general clinical application. This technology may have a major application with the emergence of modulators of growth and differentiation of haematopoietic cell lines.