We prospectively evaluated infusion-related toxicities in 70 patients undergoing autologous bone marrow transplantation. We studied symptoms, vital signs, forced vital capacities, and serum chemistry changes associated with the infusion. The bone marrow grafts were cryopreserved in 10% dimethylsulfoxide (DMSO) and stored in liquid nitrogen. All grafts were concentrated by centrifugation and the buffy-coat cells collected. Additionally, 20 grafts had mononuclear cells collected using density-gradients. Before infusion, the patients were medicated with hydration, mannitol, hydrocortisone, and diphenhydramine. The grafts were rapidly thawed and immediately infused without further manipulation. The mean volume infused to patients who received buffy-coat grafts was 6.3 +/- 1.7 ml/kg containing 0.7 +/- 0.2 gm/kg of DMSO. Patients who received density-gradient separated grafts received a product with a volume of 2.9 +/- 1.3 ml/kg containing 0.3 +/- 0.1 gm/kg DMSO. Symptoms included nausea, abdominal cramping, and flushing; patients who received buffy-coat grafts had more complaints. These patients also had mild increases in AST, ALT, and total bilirubin. Forced vital capacities were decreased in this group after the graft infusion; this change was not associated with the infusion of the density-gradient separated products. There was a significant difference (p less than 0.01) in heart rate and blood pressure changes associated with the infusions. Patients who received the larger product had a minimum heart rate of 63.3 +/- 12.4 BPM as compared to 80.7 +/- 18.0 BPM for the other patients. We found minor to moderate toxicities associated with the graft infusions, which were more severe in patients who received buffy-coat grafts. This could have resulted from the greater amounts of DMSO, cell lysis products, or volumes infused.