Of 193 children who underwent hematopoietic stem cell transplantation (HSCT) for various malignancies, 10 developed hemolytic uremic syndrome (HUS) 1 1/2-5 months later. All 10 had microangiopathic hemolytic anemia, thrombocytopenia and impaired renal function. Six of 10 presented with pericardial effusion, while three presented with hypertension. No child required plasma exchange, and all patients have survived without life-threatening long-term sequelae. By univariate analysis, the underlying diagnosis of neuroblastoma and a history of cisplatin (CDDP) administration were significantly associated with the development of HUS (P < 0.0001). By multivariate analysis using logistic regression, neuroblastoma and use of total body irradiation (TBI) as a conditioning regimen were significant contributing factors for HUS (P = 0.0001 and 0.036, respectively). Although CDDP administration could not be evaluated because of its strong correlation with the underlying diagnosis, we speculate that CDDP may enhance the nephrotoxicity of TBI, leading to a high incidence of HUS in patients with neuroblastoma.