Introduction: Basic life support (BLS) is an emergency method which includes identifying an arrest situation and starting immediate appropriate cardiopulmonary resuscitation (CPR) procedures to keep life till sufferers either recover or transported to a medical facility where advanced life support is existing. It is extremely vital that all nurses know regarding basic life support to save patients` lives. Aim of work: To assess the knowledge concerning Basic Life Support (BLS) among nursing professionals at Tanta University Hospitals. Materials and methods: A cross-sectional study was conducted for a period of 6 months upon 510 randomly chosen nurses working in various Intensive Care Units (ICUs), Emergency Department and wards of Tanta University Hospitals using stratified sampling, a self-administered validated questionnaire was used to collect data. Results: The mean of total knowledge scores was 10.92 ± 3.73, about one third (33.92%) of nurses had adequate knowledge level. A significant association was found between participants` knowledge level and their academic qualification, place of current work, previous training on BLS and duration since the last training. About 42 % of studied nurses had previous BLS training. Trained nurses had significantly higher mean total knowledge score than untrained ones (12.99±3.27 vs. 9.37±3.27, p < 0.001). Conclusion and recommendations: The knowledge level of BLS was found to be inadequate among the majority of nursing staff working at Tanta University Hospitals. Regular in-service training and recertification of BLS competency are greatly recommended as well as rotating work schedule between ICUs, Emergency departments and other non emergency hospital wards.