 A prospective, multi-center study, conducted in 5 pediatric hematology-oncology units across Israel Rambam Medical Center, Haemek Medical Center, Schneider Childrens Medical Center, Hadassah Medical Center, Soroka Medical Center. All children aged 0-18 years of age, newly diagnosed with cancer and admitted to day care or inpatient departments with fever of 38.0 C will be included in the study. Demographic, clinical and microbiological figures will be collected in each center by a research assistant supervised by the infectious disease specialist. Data will be collected according to a pre-defined Patient Data Form and entered into an electronic data base that will be analyzed accordingly. In each event of febrile episode during chemotherapy, the following data will be collected by a research assistant using a patient data form and computerized software: 