There are several side effects which have been reported during the infusion of peripheral blood progenitor cells (PBPCs) either due to the infusion or the content of the infusate. We have evaluated the side effects detected during PBPCs infusion in 194 autologous and 25 allogeneic transplantations. In autologous cryopreserved PBPCs infusion, we detected a total of forty-nine (25.25%) side effect events during and after the infusion period. Forty-six (23.71%) of these side effects were detected during the infusion period including fifteen (7.73%) cardiac side effects, which required stopping the infusion, and thirty-one (15.97%) non-cardiac side effects, which did not require cessation of the infusion. Sinus bradycardia after a minimum of 45 min after completing the infusion was seen in three (1.54%) patients. The median volume, dimethyl sulfoxide (DMSO) and total nucleated cell (TNC) content of the product were found to be significantly higher in patients with side effects compared to the group without any side effects (P<0.05). The median volume and DMSO content were found to be significantly higher in patients with cardiac side effects compared to non-cardiac side effects (P<0.05). There was no cardiac side effects in patients treated with an infusate containing 100 x 10(9) L(-1) leukocytes. We did not observe any infusion-related side effects in patients given allogeneic non-cryopreserved PBPCs. We have concluded that the volume, DMSO and TNC content of autologous cryopreserved PBPCs product are directly related to clinical side effects.