INTRODUCTION: To investigate the association of blepharitis and ischemic stroke. METHODS: This nationwide retrospective cohort study used population-based data in Taiwan. Individuals aged 20 and above with diagnosis of blepharitis was included based on electrical medical records. After exclusion of ineligible cases, 424,161 patients were identified between 2008 and 2018. The blepharitis and non-blepharitis cohorts were matched based on sex, age, and comorbidities. Multivariable-adjusted Cox proportional hazards model was adopted to calculate the hazard ratio and 95% confidence interval (CI) between blepharitis and non-blepharitis cohorts. The incidence of ischemic stroke was estimated by Kaplan-Meier analysis. RESULTS: 424,161 pairs of blepharitis cohort and non-blepharitis cohort were 1:1 propensity score matched for statistical analysis. Patients with blepharitis had significantly increased risk of ischemic stroke compared with the individuals without blepharitis (adjusted hazard ratio 1.32, 95% CI 1.29-1.34, P < 0.001). A significantly higher risk of ischemic stroke was observed in blepharitis cohort with a previous diagnosis of cancer than in those without cancer (P for interaction < 0.0001). Kaplan-Meier survival analysis revealed the cumulative incidence of ischemic stroke increased in the blepharitis cohort compared with that in the non-blepharitis cohort in 10 years (log-rank P < 0.001). The follow-up period analysis further indicated 1.41-fold adjusted hazard (95% CI 1.35-1.46, P < 0.001) of ischemic stroke within a year after blepharitis diagnosis. CONCLUSIONS: Patients with blepharitis had an elevated risk of developing ischemic stroke. Early treatment and active surveillance are suggested for patients with chronic blepharitis. Further research is required to determine the casual relationship between blepharitis and ischemic stroke, as well as the underlying mechanism.