The number of pediatric bone marrow transplantation (BMT) survivors is growing rapidly, yet little is known about the long-term neuropsychologic and psychosocial sequelae of this procedure. Using a prospective, longitudinal design, 64 pediatric patients undergoing BMT were evaluated with standardized measures of global intelligence, academic achievement and selected tests of neuropsychologic function. In addition, adjustment was assessed with parent and patient report measures of social competence, behavior problems and self-esteem. Patients were evaluated prior to admission for BMT, and again in the period 6-12 months after BMT. Longitudinal findings are reported on an initial cohort of 25 survivors. Cognitive and neuropsychologic function remained stable during the study period. The few significant changes from baseline which were observed were in the direction of improvement, and may be attributed to practice effects. In contrast, declines were observed in patient social competence, self-esteem and general emotional well-being. BMT conditioning regimens appear not to be associated with significant neuropsychologic impairment in the first year after transplant. However, a longer period of follow-up is necessary before neuropsychologic late-effects can be ruled out. The first year after BMT is characterized by significant psychosocial difficulties for survivors. Adjustment issues may provide a more salient focus of study during this time frame.