Narrowing and other changes in retinal arterioles may reflect damage due to hypertension, which may predict stroke and other cardiovascular diseases independently of blood pressure level. Newly developed quantitative methods of assessing retinal narrowing are used to determine whether this sign is related only to current blood pressure or whether it also independently reflects the effects of previous blood pressure. Retinal photography was performed at the third examination of Atherosclerosis Risk in Communities (ARIC) Study in 1993-1995, and results are presented for the 9,300 nondiabetic participants aged 50-71 years. Generalized narrowing of smaller arterioles was strongly and monotonically related to current blood pressure in men and women, whether they were taking antihypertensive medications or not, and, independent of current blood pressure, was consistently and monotonically related to blood pressure levels measured 3 and 6 years before the retinal assessment. Arteriovenous nicking was also independently related to both current and previous blood pressures. The patterns of association suggested that these signs reflect both transient and persisting structural effects of elevated blood pressure, in agreement with the scant pathologic literature available. The findings suggest that retinal assessment may be useful for research on the microvascular contributions to clinical cardiovascular diseases.