Background: A significantly greater proportion of patients who died due to aspiration pneumonia were diagnosed with in-hospital aspiration pneumonia (19%), compared to those who were improved or died due to all other causes. Incidence and major predictors were not known clearly, especially in our country Ethiopia. Objective: To determine incidence and predictors of aspiration pneumonia among adult traumatic brain injury patients at Felegehiwot comprehensive specialized hospital, Bahirdar, North west Ethiopia, 2021. Methods: Institution based retrospective study was conducted from all adult traumatic brain injury patients who were admitted at Felegehiwot comprehensive specialized hospital in the past five years (January 1, 2015- December 31, 2020) for 51 days of survival. Descriptive statistics were used to describe patient characteristics. Kaplan-Meier survival curve and log-rank test were used to test for the presence of difference in survival among patients categorized differently with different characteristics. Cox proportional hazard regression model was used at 5% level of significance to determine the net effect of each explanatory variable on incidence of aspiration pneumonia after admission because of traumatic brain injury. Result: A total of 396 patients aged >15 years diagnosed and admitted as traumatic brain injury in the past 5 years were included. Seventy patients (17.67%) were developed aspiration pneumonia providing incidence rate of 32.39(95% CI: 25-62-40.94) per1000 person days of observation. The overall median survival time could not be determined. The overall estimated survival rate was 77.68% (95% CI: 72.07-82.30) at 51 days of follow-up. Independent predictors in development of aspiration pneumonia for admission due to traumatic brain injury were being referral AHR (2.43; (95% CI: 1.12-5.25)), nasogastric tube insertion AHR (3.02; (95% CI: 1.43-6.39)) and baseline Glasgow comma scale <8 AHR (3.88; (95% CI: 1.42-10.062)). Conclusion: Traumatic brain injury induced aspiration pneumonia in this study was an important health issue. Being referral, nasogastric tube insertion and low baseline Glasgow comma scale were significant predictors of incidence of aspiration pneumonia. It is better to improve prehospital and hospital care, first aid service and comma care during transportation and admission time. Prospective studies to cover limitations are recommended. Key words: Aspiration pneumonia, Traumatic brain injury, Bahirdar, Ethiopia