Few studies have examined the effect of parental BMT on the family and less is known regarding the impact on children. The purpose of this prospective study was to increase understanding of children's adaptation to the stress of parental BMT across a 12-month trajectory. Data were obtained from 61 children ages 10-18 before parental transplant, during parental hospitalization, 1, 4 , 8 and 12 months post BMT. Mixed linear modeling was used to analyze longitudinal data from children nested within families. Analyses examined change in child emotional adaptation, points of greatest vulnerability throughout the BMT trajectory and the impact of theoretically relevant variables on their adaptation. Children's emotional adaptation became significantly more positive over time, although their level of distress remained above the norm. Pre-transplant was the period of greatest emotional distress. Negative self-esteem, disruption within the family structure, use of disengagement coping and the mother as transplant recipient were associated with more negative adaptation. Further research is needed to fully understand the effects of parental BMT on children. However, these findings point to the importance of considering the adaptation of children and its implications for the development of preventive family interventions for this vulnerable population.