Renal artery stenosis (RAS) is recognized as a major co-morbid condition for patients with cardiovascular disease. Although the prevalence of RAS in Western countries has been reported as 13.5-18% in patients with suspected coronary artery disease (CAD) undergoing coronary angiography, there is little information available about the prevalence of RAS in Asian populations, which are less susceptible to atherosclerosis. To evaluate the prevalence of RAS in Japanese patients suspected of cardiovascular disease and the relationships among RAS and vascular risk factors, especially hypertension, renal artery angiography was performed in a total of 289 consecutive patients receiving diagnostic cardiac catheterization. RAS with a stenosis diameter greater than 50% was considered significant. The prevalence of RAS was 21/289 (7%) including 18 (6%) cases of unilateral stenosis and 3 (1%) of bilateral stenosis. RAS accompanied 14/220 (6%) cases of CAD, 4/34 (12%) cases of valvular heart disease and 1/14 (7%) cases of cardiomyopathy. In the subgroups of CAD, the prevalence of RAS was 5%, 10%, 9%, and 19% in cases of 0, 1, 2 and 3-vessel disease, respectively. Hypertension was more frequent among patients with than among those without RAS (86% vs. 45%, p=0.0003). The prevalence of RAS was 13% in hypertensives and 2% in normotensives (p = 0.004). Thus RAS was frequent in patients with established CAD, and particularly in those with 3-vessel disease. Together, the results showed that hypertension was closely associated with RAS, appearing as both a risk factor and a possible clinical manifestation of the disease. We conclude that more attention should be paid to RAS in Japanese patients with hypertension and cardiovascular disease.