Background: Cancer is a group of diseases characterized by uncontrolled growth and spread of abnormal cells. If has been categorized as a chronic disease that is characterized as a prolonged course, which does not resolve spontaneously and for which a complete cure is rarely achieved.so, this study aimed to assess needs and problems of children undergoing chemotherapy and their caregivers. Design: A descriptive study exploratory design was used to conduct this study. Subject: A purposive sample composed of 100 children undergoing chemotherapy. Settings: this study was carried out in Oncology Units in Children Hospital affiliated to Ain Shams University Hospitals and Minia Oncology Center over six months. Tools: two tools were used to collect necessary data, Interview questionnaire sheet and children' needs and problems sheet. Result: more than two thirds of the studied caregivers had unsatisfactory level of total knowledge while this study revealed that more than third of studied children had high needs. Also, more than half of studied children had severe problems related to cancer and chemotherapy. Conclusion: Based on the results of the current study, it can be concluded that, more than half of studied children had high total needs of psychological & social, cognitive & mental, and medical needs and less than two thirds of them had severe problems related to cancer and chemotherapy. Moreover, it was found that three quarters of the studied caregivers had unsatisfactory level of total knowledge about cancer and chemotherapy. In addition, there was highly statistically positive correlation between the needs of the studied children and their problems. Also, there was statistically positive correlation between the knowledge of the studied caregivers and the needs and problems of their children. Recommendation: Further research study is recommended to assess needs and problem of children undergoing chemotherapy and their caregiver.