The objective of this study was to describe associations of retinal arteriolar abnormalities with clinical and subclinical manifestations of atherosclerosis and a broad group of risk factors for vascular disease. A biracial population of 8772 adults (aged 48 to 72 years) living in 4 communities was examined from 1993 to 1995 were studied for that purpose. Retinal arteriovenous nicking and focal arteriolar narrowing were determined by light-box grading of a 45 degrees fundus photograph by use of a standardized protocol. Diameters of arterioles and venules were measured in digitized photographs, and a summary arteriolar-to-venular ratio was derived as an index of generalized arteriolar narrowing. Focal arteriolar narrowing was associated only with hypertension. Generalized arteriolar narrowing was associated with carotid plaque but not with any other evidence of atherosclerosis, either clinical (cardiovascular disease or stroke) or subclinical (carotid or popliteal artery thickness or lower limb obstructive disease), or with plasma cholesterol. It was also associated with smoking, with inflammatory markers (white blood cell count, fibrinogen, and reduced albumin), and with the triglyceride and high density lipoprotein cholesterol changes associated with inflammation. Arteriovenous nicking was inconsistently associated with subclinical atherosclerosis. It was not associated with cardiovascular disease, stroke, or plasma cholesterol. Arteriovenous nicking was associated with markers of inflammation and vascular endothelial dysfunction (von Willebrand factor and factor VIII). Arteriolar narrowing and nicking appear to be related to hypertension and inflammatory factors. Nicking may also be related to endothelial dysfunction. Results suggest that these arteriolar changes are pathologically distinct from atherosclerosis. Including their measurement in population studies may permit evaluation of the independent contribution of arteriolar disease to various ischemic diseases of the heart, brain, and other organs.