OBJECTIVE : Aspiration pneumonia is a leading cause of death among older patients; however, little is known about the long-term mortality in aspiration pneumonia. The purpose of this study was to evaluate long-term mortality and its associated factors in patients with aspiration pneumonia. METHODS : Retrospective cohort study. METHODS : In total, 550 patients with aspiration pneumonia (median age: 78.0 years, 66.4% male) with compatible clinical symptoms and chest computed tomography images were enrolled at a single tertiary center from 2006 to 2016. METHODS : The 1-, 3-, and 5-year mortality rates were evaluated for all patients. The prognostic factors for 1-year and 5-year mortality were also evaluated using Cox proportional hazard models. RESULTS : A total of 441 (80.2%) patients died during a median follow-up of 50.7 weeks. The 1-, 3-, and 5-year mortality rates were 49.0%, 67.1%, and 76.9%, respectively. Multivariate analysis identified 5 risk factors for 1-year mortality of male sex [hazard ratio (HR) 1.533, P = .003], low body mass index (HR 0.934, P = .002), hypoalbuminemia, anemia (0.973, P = .032), and mechanical ventilation (HR 2.052, P < .001), which were also independent prognostic factors for 5-year mortality. During the follow-up period, 133 (24.2%) patients experienced recurrent aspiration pneumonia. However, Kaplan-Meier analysis showed no significant differences in survival curves between patients with single and recurrent aspiration pneumonia (P = .371). CONCLUSIONS : Long-term prognosis of aspiration pneumonia was poor as a result of underlying morbidity instead of the aspiration pneumonia itself. Our findings suggest that prognostic indices for patients with aspiration pneumonia including the patient's underlying conditions should be devised.