Despite the great medical advances that now mean that BMT cures many patients, the difficult reality is that not all children survive transplant. The diseases that lead to the need for BMT are life-threatening, and the procedure itself still comes with risk of serious complications and potentially-dangerous side effects. Patients undergoing BMTs with cells from unrelated donors face extra challenges. While we hope that no family will have to have confront this issue, it would not be realistic to discuss BMT without acknowledging this reality.