Our objective was to compare cognitive, educational and psychosocial outcomes, and quality of life (QOL) of pediatric hematopoietic SCT (HSCT) survivors with those of their siblings, 2 years post-HSCT. Forty-six HSCT survivors, with age ranging from 3 to 16 years, and 33 siblings, with age ranging from 3 to 20 years, participated. Standardized tests were performed and questionnaires were completed by the participating children and their mothers. Survivors' full, verbal and performance IQ scores did not differ significantly from those of their siblings. Survivors, however, had significantly higher perceptual organization scores than their siblings. Siblings' mean scores on spelling were significantly higher than those of survivors, but arithmetic and reading scores were not. Siblings had significantly more internalizing problems than survivors. Siblings' physical QOL scores were significantly better than those of survivors. Finally, child age, maternal depression scores and age, and family cohesion were related to cognitive and educational differences. A history of cranial radiation and a diagnosis of neuroblastoma or Hodgkin's lymphoma in survivors were related to the difference in internalizing scores. Except for some deficits in educational outcomes and physical QOL, survivors' cognitive and psychological outcomes at 2 years post-HSCT were similar to those of their siblings. Family and clinical factors were identified as critical for these outcomes.