Advances in the specialty of pediatric oncology have significantly improved the prognosis of children with cancer. Since their disease is no longer imminently fatal, their families must face the challenge of coping with a life altered by cancer, its sophisticated treatment regimen, and the accompanying uncertainties the disease brings. Most of the literature focuses on the impact of the illness on the sick child and the parents, rarely mentioning its effects on the healthy siblings. However, the well brothers and sisters are in a unique position, often being the primary target of family disequilibrium. Therefore, this article takes a developmental approach in describing the siblings' perspective, identifying their characteristic responses and special needs. Specific recommendations aimed at promoting the well siblings' adjustment are offered; health care professionals can play an important role in helping parents better understand the types of feelings, behaviors, and stresses experienced by the healthy siblings.