Children who require a marrow transplant may receive such hematopoietic cells from one of many sources. This study reviews the experience of one center with 58 children who received marrow from unrelated donors over a 10- year period. These children had a variety of malignant and non-malignant diseases. During that time period, only three of these children had failed to meet engraftment criteria. All donor marrow specimens were T-lymphocyte- depleted using an antibody/complement methodology. No difference was demonstrated in outcome between donors who were perfectly HLA-DR-DNA matched versus those who were only partially matched. The increased size of various marrow donor registries has increased the number of potential donors available for these patients. The lack of a requirement for perfect matching means that there is an ever-increasing number of donors available. No graft- versus-host disease (GvHD) or grade III-IV GvHD was associated with a poorer outcome. Stable, long-term engraftment with minimal morbidity has been demonstrated in these children as evidenced by stability of survival curves by two years after marrow transplant.