Although infusion of cryopreserved bone marrow or peripheral blood stem cell is associated with a variety of symptoms, there have been no reports detailing the data of infusion-related toxicities of cryopreserved cord blood (CB) units. We prospectively evaluated the incidence and significance of infusion-related toxicities in 34 adult patients undergoing unrelated CB transplantation. Cryopreserved CB units were thawed and immediately infused, unfiltered, through a central intravenous catheter without further manipulation. Heart rate, blood pressure, oxygen saturation and clinical symptoms were recorded during and after infusion. Twenty-four percent of patients experienced non-cardiovascular toxicities related to infusion. The incidence of systolic and diastolic hypertension and bradycardia was 58, 64 and 32%, respectively. Although three patients (9%) with severe systolic hypertension after the infusion required treatment with antihypertensive agents, no patients experienced life-threatening side effects or needed discontinuation of CB unit infusion. Patient or transplant characteristics had no effect on the hypertension and bradycardia related to the infusion of CB. These data suggest that infusion of cryopreserved CB without further manipulation after thawing is safe and well tolerated. However, cardiovascular toxicities including hypertension and bradycardia were frequently observed.