Infection causes significant morbidity and mortality in children with cancer. Cancer patients are at unusually high risk for developing infections which are a major cause of in-hospital morbidity and mortality. The predisposition of infection in malignant patient is mediated through various abnormalities including both the immune defects inherent in the primary disease and in further immunosuppression related to the management.This cross sectional study was carried out to find out the pattern of infection in pediatric oncology wards at NCI, Cairo University, to determine the frequency and types of risk factors predisposing to infection and to determine the impact of that infection on mortality of pediatric oncology patients. The study included 175 pediatric cancer patients with proved infection, the cases were drawn from the inpatient department at the NCI, Cairo, including free and insurance sectors. The analysis showed that: The commonest evident focus of infection was mucositis (83.43%), followed by GIT (45.14%) and then chest infection (26.86%). The most common organisms were: Gram positive organisms account for (58.2%) corresponding to (39.8%) of Gram-negative organisms.The mortality rate was (10.3%) and the Predicting factors for infection were as follow: the residence of the patients whether rural or urban, socioeconomic state of the patients measured by crowdeness index, socioeconomic state of the parents, chest infection and intensified protocols of chemotherapy