Information regarding the association between prehypertension BP level and renal arteriosclerosis is limited. In 652 consecutive population-based autopsy samples without hypertension treatment before death, the relationship between the severity of renal arteriosclerosis and BP levels classified according to the criteria of the Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure was examined. The age- and gender-adjusted frequencies of renal arteriosclerosis linearly increased with elevating BP levels; both hypertensive and prehypertensive subjects had significantly higher frequencies of renal arteriosclerosis than subjects with normal BP (normal 11.9%; prehypertension 28.5%; stage 1 hypertension 32.9%; stage 2 hypertension 58.2%; all P < 0.01 versus normal). In a logistic regression model, prehypertension was significantly associated with renal arteriosclerosis after adjustment for other cardiovascular risk factors (prehypertension multivariate-adjusted odds ratio [mOR] 5.99 [95% confidence interval (CI) 2.20 to 15.97]; stage 1 hypertension mOR 6.99 [95% CI 2.61 to 18.72]; stage 2 hypertension mOR 22.21 [95% CI 8.35 to 59.08]). This significant association was observed for all renal arterial sizes. The similar association was also observed for arteriolar hyalinosis. When the subjects were divided into those with and those without target organ damage, the impact of prehypertension on renal arteriosclerosis was similar for both groups (subjects without target organ damage mOR 5.04 [95% CI 1.36 to 18.62]; subjects with target organ damage mOR 6.42 [95% CI 1.29 to 32.04]). These findings suggest that both hypertension and prehypertension are associated significantly with the severity of renal arteriosclerosis, regardless of the presence or absence of target organ damage.