Background: Despite general recognition that enteral tube feeding (ETF) is frequently employed in long-term care facilities and patients with dementia, remarkably little research has determined which factors are associated with its use in acutely ill older adults. In this study, we aimed to investigate determinants of ETF introduction in hospitalized older adults. Methods: We examined a retrospective cohort of acutely ill patients, aged 60 years and older, admitted to a university hospital’s geriatric ward from 2014–2015, in São Paulo, Brazil. The main outcome was the introduction of ETF during hospitalization. Predictors of interest included age, sex, referring unit, comorbidity burden, functional status, malnutrition, depression, dementia severity, and delirium. Multivariate analysis was performed using backward stepwise logistic regression. Results: A total of 214 cases were included. Mean age was 81 years, and 63% were women. Malnutrition was detected in 47% of the cases, dementia in 46%, and delirium in 36%. ETF was initiated in 44 (21%) admissions. Independent predictors of ETF were delirium (odds ratio [OR], 4.83; 95% CI, 2.12–11.01; P < .001) and total functional dependency (OR, 8.95; 95% CI, 2.87–27.88; P < .001). Malnutrition was not independently associated with ETF. Conclusion: One in five acutely ill older adults used ETF while hospitalized. Delirium and functional dependency were independent predictors of its introduction. Risks and benefits of enteral nutrition in this particular context need to be further explored.