The authors examined the relation of narrowed retinal arteriolar diameters, a marker of hypertensive damage, to mortality in a population-based cohort of 4,926 persons aged 43-84 years living in Wisconsin. A computer-assisted method was used to measure retinal vessel diameters from digitized retinal photographs taken at the baseline examination (1988-1990). These measurements were summarized as the retinal arteriole-to-venule ratio (AVR), with a smaller AVR indicating narrower arterioles compared with venules. Its relation to 10-year mortality was analyzed by using Cox proportional hazards models, adjusting for age, gender, blood pressure, diabetes, and other risk factors. No relation was found between smaller AVR and increased mortality. In relation to the largest AVR quartile, the adjusted relative risks of all-cause mortality were 0.93 for the smallest AVR quartile, 0.71 for the second AVR quartile, and 0.80 for the third AVR quartile. Results were largely similar in analyses of cause-specific mortality (vascular disease and non-vascular-disease mortality) and in subgroups stratified by age, gender, and diabetes and hypertension status. These data contrast with recent studies showing a relation between narrowed retinal arterioles and increased cardiovascular risk, suggesting that further research is needed to understand the systemic associations of retinal microvascular changes.