The analysis of arterial blood gases plays an important role in making correct diagnosis and deciding management strategies in critically ill patients. Nurses are often the first member of the health care team to see arterial blood gas results and are playing a bigger role in the realm of blood gas analysis within the work area, particularly as more analyses are placed in these areas. Aims and Objectives: The objectives of the study were to assess the level of Knowledge regarding Arterial blood gases analysis among staff nurses and to find out the association between knowledge score regarding Arterial blood gases analysis among staff nurse with selected demographic variables. Material and Methods: A non– experimental descriptive research design was used. Total of 60 staff nurses working in SGT Hospital, Budhera, Gurugram who met the inclusion criteria were selected using convenient sampling technique. The tools consist of demographic variables and structured knowledge questionnaire which consists of 30 multiple choice questions. Reliability of the tool was established by spit–half method followed by Pearson’s correlation. Ethical permission was obtained from ethical committee SGT University and the written consent was obtained from each study participants before administering the tool. Results: The findings of the study indicated that half (50%) Staff nurses were in age group 20–28years, 33.5% of Staff nurses were GNM Nursing. most (68%) of Staff nurses were female, 33.4% of Staff nurses were working in ICU Area and nearly half (46.6%) of Staff nurses were 1–3 years of experience. Study findings also revealed that there was significant association between knowledge score with selected demographic variables. Conclusion: It was concluded that there was significant association between knowledge score with selected demographic variables such as age, gender, educational status and years of experience.