Background: Aphasia negatively impacts quality of life. This is the first Brazilian study that investigates the prevalence of aphasia and its related factors, the results of which may underpin hospital and health service planning for this vulnerable population.Objective: To establish the prevalence of aphasia in patients after first-ever ischemic stroke (FEIS) and associated factors.Methods: This is a retrospective cohort study, based on a database held in Joinville, Brazil. All cases of FEIS admitted to one public hospital in Joinville in 2015 were selected. The diagnosis of aphasia was verified by neurologists through the language item of the National Institute of Health Stroke Scale (NIHSS).Results: Of the 350 patients with FEIS, 79 (22.6%) had aphasia. Patients with aphasia (PWA) were older, with a higher likelihood of dysarthria, more thrombolytic use, and greater stroke severity. PWA had higher mortality than patients without aphasia (24.1% versus 10.7%, p = .004) and longer hospitalization time (21.32 versus 17.46 days, p = .009). Higher NIHSS score was an independent predictor for the occurrence of aphasia on admission (OR 1.24, 95% CI 1.17-1.31, p < .001). Older age (OR 1.06, 95% CI 1.03-1.09, p < .001) and stroke severity by NIHSS (OR 1.19, 95% CI 1.12-1.25, p = <0.001) were independent predictors of death.Conclusions: PWA may need more health care during hospitalization, because of the severity of the stroke, and their frailty. Further studies are needed to assess the direct impact of aphasia on inpatients.