Introduction: Airway management in critical care units, such as ICUs, A&Es and Anesthesiology Departments, includes nursing procedures that require expert knowledge and skills. These two key elements remain a controversial clinical area as they have not been studied in Greece. Aim: To evaluate the level of knowledge in airway management of nurses working in ICU, A&E and Anesthesiology Departments. Material and Methods: A cross-sectional study was conducted using a self-administered questionnaire which was distributed to a sample of 211 nurses working in 24 departments (ICU, A&E and Anesthesiology) in 8 hospitals of Northern Greece. The knowledge test tool consisted of 25 closed-ended knowledge questions. The mean score (0-25 scale), knowledge level, ratings relationship with other demographic data, as well as some possible causal factors as independent variables for interpreting the variation of scores were calculated. Results: The research tool showed satisfactory reliability (Cronbach's α=0.706) and content validity (CVI = 0.907). The average knowledge score of the sample was 16.87 and this level was rated as "very good". Differences in ICU, Anesthesiology and A&E scores were mainly attributed to the background and expertise of the nurses. Multiple regression identified specific hospitals, department, type of hospital (provincial or big city), frequency of training, empirical (professional) knowledge, BLS and ILS certification as independent variables for interpreting the variation in the level of the nurses’ knowledge. Conclusions: Overall, the knowledge of airway management of the nurses in this study is considered ‘good’ to ‘very good’. However, it is necessary to incorporate on a regular basis a continuous and specialized training program, at least in some critical care units. Factors affecting the theoretical performance of nurses need to be further studied for safe conclusions.