Background: Associated diseases and risk factors are the major causes of postoperativerncomplications after cardiothoracic surgery. Outcome of Cardiothoracic surgery isrngenerally associated with high incidence of myocardial, neurological, renal dysfunction,rnbleeding, surgical site infection which account up to 10% mortality depending on age, sex,rncomorbidity, preoperative medication and reoperation. rnObjective: To assess the determinants of cardiothoracic surgery outcomes at TikurrnAnbessa Specialized Hospital Addis Ababa Ethiopia. rnMethodology: A retrospective institutional based cross-sectional study design wasrnconducted among 323 randomly selected patient records. Systematic random samplingrntechnique was used to select medical records. Data was gathered from the medical recordsrnof cardiothoracic patients registered during the past five years (from November 2015-rnNovember 2020) using a pretested checklist. rnResult: Male participants were found to be involved more than female participants. Thernfollowing were final predictors of cardiothoracic surgery outcomes. Ages between 18 andrn28, 1.398 times more likely to develop poor outcomes postoperative compared to the restrnage groups. [AOR=1.398, 95% CI=1.179-1.656]. Patients with chronic pulmonary diseasernare 1.713 times more likely to develop poor outcomes as compared to patients with otherrncomorbidities and no known comorbidities [AOR=1.713, 95% CI=1.041-2.818]. Andrnpatients whose duration of surgery is 2-3hrs 2.306 times more likely to develop poorrnoutcomes postoperative as compared to 3-4hrs duration of surgery [AOR=2.306 95%rnCI=1.241-4.283]. Personal habits, waiting time for surgery since admission lost theirrnsignificance.rnConclusion: In this study age, comorbidities (chronic pulmonary disease), and durationrnof surgery were factors associated with the outcomes. Further investigation duringrnperioperative period like adjusting medications, chest physiotherapies, preoperative andrnpostoperative patient care in order to reduce the poor outcomes.