Obesity Fatigue is a common problem in cancer pediatric patients. Fatigue in childhood cancer is a pervasive and distressing symptom described as a “lack of energy. Aim of study was to assess the perception of cancer related fatigue among pediatric patient undergoing cancer therapy. Settings: The study was carried out in the chemotherapy pediatric units and a bone marrow transplantation unit of Ain Shams Children Hospital affiliated to Ain Shams University Hospitals. Subject: A purposive sample included 70 children in the previous mentioned settings. Tools of data collection:A predesigned questionnaire format to assess children's knowledge about cancer-related fatigue, children's fatigue assessment sheet to assess children's fatigue during and after cancer therapy session and Children's perception fatigue scale to assess the children's perception of cancer related fatigue. Results:This study revealed that, more than half of studied children with chemotherapy were having moderate fatigue, also more than half of studied children who treated by bone marrow transplantation had the extreme fatigue. Conclusion: Based on the study researcher questions, it can be concluded that, Fatigue has been identified by children and adolescents who are receiving treatment for cancer as one of the most distressing treatment-related symptoms they experience. Recommendation: Develop studies about the perception cancer related fatigue and apply these studies in professional practice with a view to enhancing the evidence of these symptoms and furthering the quality of life of child and adolescent cancer.