Marrow red cells (MRBCs) from 56 autologous bone marrow harvests were rescued after processing and transfused as the sole transfusion support after surgery. There was no correlation between volume of harvest and total mononuclear cell (MNC) count. The marrow collection induced a significant decrease in hematocrit values (mean, 6.1; range, -0.3-12.3; p less than 0.001) unrelated to the patient's diagnosis, age, or gender. Processing of the marrows resulted in a mean transfused MRBC mass of 258 mL (range, 101-494 mL), representing 78 percent (range, 43-100%) of the MRBC mass collected. The amount of MRBCs transfused correlated with total MNC count (p less than 0.01). All autologous MRBC transfusions were well tolerated. It can be concluded that autologous MRBC transfusions are safe and may eliminate the need for homologous blood transfusions after marrow harvest.