The purpose of this article is to outline how the disease, treatment, and psychological state of a child with cancer impact on the child's nutritional status. The methods of assessing nutritional status, including anthropometric measurements, laboratory indices, clinical observation, dietary assessment, and psychosocial evaluation, are summarized. After nutrition assessment, the pediatric oncology nurse and the dietitian, along with the oncologist, the family, and the child, develop a plan of care. The specific roles of the pediatric oncology nurse and dietitian in the nutrition intervention are described.