Background: Post-operative pain management is one of the key responsibilities of health rnprofessionals. Failure to manage post-operative pain effectively will lead to increase morbidityrnand mortality, long hospital stay, increase health care cost, and patient dissatisfaction. Despiternimproved understanding of pain mechanism, advances in pain management approach, and otherrnfocused initiatives large proportion of post-operative patientâ€™s reports pain after surgery. rnTherefore the major aim of this study was to assess pain severity and associated factors amongrnpost-operative adult patients in public hospitals of Addis Ababa.rnMethods and materials: Facility-based cross-sectional study was conducted. The singlernpopulation proportion formula was used to calculate the sample size. A total of 414 studyrnparticipants were involved. Simple random sampling was used to select study participants. Therndata was collected by the standard questioner and checklist. The collected data were entered,rncleaned, and analyzed by SPSS version 24.0 statistical software. Descriptive results werernpresented by tables and figures. Bi-variable analysis was employed to select independentrnpredictors of pain severity and multivariable regression used to measure the association betweenrnindependent and dependent variables. On bi-variable analysis, those variables with a value lessrnthan 0.20 were entered on multi-variable analysis. Finally, variables with a p-value < 0.05 wererndeclared as independent predictors of the outcome variables. The model fitness test was checkedrnby Hosmer and Lemeshow's goodness-of-fit test. rnResults: a total of 406 study participants have responded to the interview giving a response raternof 98%. The overall incidence of moderate to severe pain was 85.5%. Preoperative analgesiarnadjusted odds ratio (confidence interval), 0.236(0.065-0.863), preoperative anxiety, 5.468(1.34122.303),rngeneralrnsurgeryrn7.627(1.901-30.602),rnorthopedicsrnsurgery,rn7.195(1.055-49.094),rnsizernofrnrnthernincision,rn5.086(1.352-19.135),rnandrnpost-operativernanalgesia;rnnonernsteroidalrnanti-inflammatoryrnrndrugsrnrn5.611(2.000-15.737), and tramadol, 4.714(1.506-14.753) was independent predictors ofrnpostoperative moderate to severe pain.rnConclusion: - The study revealed that the overall incidence of postoperative pain was high in thernstudy area. This reflects attention given to postoperative pain management is low. Preoperativernanalgesia, preoperative anxiety surgery type, incision length, and postoperative analgesia werernindependent predictors of postoperative pain.