A review of 33 consecutive autologous bone marrow transplant (BMT) cases revealed three cases of acute renal failure which developed immediately following reinfusion of cryopreserved bone marrow, and which could not be explained on the basis of hypotension or nephrotoxic drugs. Gross hemoglobinuria was noted in all 33 autologous BMT patients, and may have contributed to the acute renal failure seen in the three patients. Histologic examination of the kidneys of one patient who died 3 days after BMT showed markedly dilated renal tubules filled with hemoglobin casts. The kidneys of the other two patients, who died 8 and 20 days after BMT, showed renal tubular necrosis and regeneration with numerous hemoglobin casts. All three patients had systemic candidiasis at autopsy, and there is evidence to suggest that the infection was also present at the time of BMT. Fungal sepsis may have predisposed these patients to the development of acute renal failure. We recommend the use of procedures that minimize the hemolysate content of cryopreserved bone marrow.