Background: Effective pain management requires precise knowledge, attitude and rncompetent assessment skills. Nurses should have basic knowledge and develop a positivernattitude towards post-operative pain management. Little is known about the knowledge andrnthere is no evidence to understand the attitude gaps and nurses' practices of postoperative painrnmanagement by nurses working in federal hospitals. rnObjective: to examine the level of knowledge, attitude, practice and associated factors ofrnnurses towards POPM in four federal hospitals in Addis Ababa Ethiopia 2020. rnMethod: Institution-based cross-sectional study was conducted among 103 nurses at federalrnhospitals. The total sample sizes were allocated proportionally based on the number of nurses rnfrom each hospital. A simple random sampling technique was employed for the selection ofrnstudy participants. Data were collected by using self-administered structured questionnaire andrnwere checked, cleaned and entered into Epi data version 3.5 and imported to SPSS version 25.0rnsoftware for analysis. Associations between independent and dependent variables werernanalyzed by using descriptive statistic & a binary logistic regression model. rnResult: The overall finding of the study revealed that nurses had poor knowledge (51.5%),rnfavorable attitude (58.5%), and poor practice (48.5%)towards post-operative pain rnmanagement. Gender, training and favorable attitude (p-value=0.024, 0.003, 0.002rnrespectively) were found to be statistically significant with nurses knowledge of post-operativernpain management. Knowledge of nurses had significant association with attitudes of nurses. rnAttitude, organizational protocol to pain management and knowledge of nurses had significantrnassociat ion wit h nursesâ€™ pract ice of POPM. rnConclusion: The result of this study showed that nurses in federal hospitals have poorrnknowledge, poor practice and favorable attitude towards post-operative pain management