Nutrition disorders affect the health status of the children with leukemia. Children more susceptible for infection, make children not response well to treatment, and increase side effects. Aim of the study: This study aimed to assess the mothers' knowledge about the nutrition of the children with leukemia. Subjects and method: A descriptive exploratory research design was used to perform this study. The study subjects included a convenience sample of 100 mothers with their children suffering from leukemia attending the Unit of Pediatric Oncology Department (POD) at South Egypt Cancer Institute- Assuit University. Data were collected by utilizing two tools; Tool (1):- Children and parents' profile, Tool (2): Question sheet to assess the mothers' knowledge regarding nutrition of children with leukemia. Results: The highest percentage of the studied mothers had poor knowledge about nutrition for their children suffering from leukemia. The majority of them had unsatisfactory knowledge about the disease itself. Conclusion: Mothers had poor knowledge about nutrition and leukemia treatment. Recommendations: Workshop training programs for nurses on how to help caregivers to cope appropriately with their children to reduce the emergence of nutrition problems.