OBJECTIVES: To examine the association between retinal microvascular signs, as a proxy for cerebral microvascular disease, and cognitive impairment. DESIGN: Cross-sectional population-based study. SETTING: Urban population survey PARTICIPANTS: One thousand nine hundred eighty-eight persons aged 49 to 97. MEASUREMENTS: All participants underwent retinal photography and had the Mini-Mental State Examination (MMSE) administered by trained personnel. Retinal photographs were masked and graded for retinopathy signs (microaneurysms, hemorrhages, hard exudates, cotton wool spots), and retinal vessel calibers were measured using a validated computer-assisted method. Cognitive impairment was defined as an MMSE score of 23 or less, in line with other epidemiological studies. RESULTS: Cognitive impairment was present in 121 participants (6.1%). In the total population, after adjusting for age, sex, blood pressure, diabetes mellitus, smoking, cardiovascular disease, education, and other factors, retinal venular dilation was associated with cognitive impairment (odds ratio (OR)=1.8, 95% confidence interval (95% CI)=1.0-3.2, P=.03). In persons with hypertension, retinopathy signs (adjusted OR=1.7, 95% CI=1.0-3.2, P=.05) and retinal venular dilation (adjusted OR=2.7, 95% CI=1.2-6.1, P=.01) were associated with cognitive impairment. CONCLUSION: Retinal microvascular signs are associated with significant cognitive impairment, particularly in older persons with hypertension. These findings suggest that cerebral microvascular changes may contribute to cognitive deterioration.