Background: Trauma is a major cause of mortality and disability in developed as well asrndeveloping countries. The ATLS knowledge helps to implement a methodological approach to therntrauma patients in the emergency room which aims for rapid and accurate assessment. Traumarnmanagement can be improved by implementing ATLS properly. However, for the knowledge ofrnthe investigator, there is a limitation of a study conducted in Ethiopia.rnObjective: To assess the knowledge of nurses on ATLS working in the adult emergencyrndepartment of TASH and ALERT, Addis Ababa, Ethiopia, 2021.rnMethods: A descriptive cross-sectional study design was used and data were collected using arnstructured and self-administering questionnaire. The study population was all nurses workingrnwithin the adult emergency department of the ALERT and TASH. Participants were selected byrnconvenience sampling technique. The collected data were checked for its completeness by datarncollectors and PI before entering into the software for analysis. Data were entered using the epidatarnv 4.6.0, and analyzed using SPSS v26. Binary logistic regression was performed to see thernassociation between the independent and dependent variables. A P-value of less than 0.05 isrnconsidered statistically significant.rnResult: One hundred nurses participated in the study. The majority of them were between thernages of 25 and 29 years, 59% with mean age of 29.5Â±5.4. There were equal numbers of bothrnsexes out of totally participated subjects, but the most participants were from TASH (56%) whilernthe rest were from ALERT. Educational and the training status of the nurses are identified as thernfactors affecting the knowledge level of the respondents (AOR=12.3,P=0.022 and AOR=2.47, P=rn0.001)respectivelyâ€™. From study participants, only 45% of the nurses have good knowledge ofrnATLS.rnConclusion and recommendation: in conclusion, there is a significant gap of knowledge towardsrnATLS in these selected hospitals. . A lack of ATLS expertise among emergency department staffrnnurses could potentially harm patient outcomes in trauma cases. Therefore ALERT and TASHrnnurses should get training on ATLS & improve their educational status.