The incidence of renal artery stenosis (RAS) in patients with coronary artery disease (CAD) has not been well documented. Over a 9-month period, 196 patients who underwent coronary angiography because of clinically suspected CAD had routine nonselective renal cine or digital subtraction angiography. There were 68 females and 128 males with a mean age of 63 years (range 35-85). Angiographically significant CAD was present in 152 patients (78%). Of the total patient cohort, 29 patients (15%) had mild RAS (< 50%), and 36 patients (18%) had significant RAS (> or = 50%). In patients with normal coronary arteries, only three patients (7%) had RAS. Thirty-three patients (92%) with severe RAS also had CAD. Of these 33 patients, 45% had hypertension, 30% had hyperlipidemia, 24% had diabetes mellitus, 24% had renal insufficiency (creatinine > or = 1.5), and 51% were smokers. In addition, it was noted that 20 of these patients (61%) had two or more of the above-listed clinical parameters. However, univariate analysis using the chi-square test revealed that only CAD (22% P < 0.03) and renal insufficiency (29% P < 0.15) were reliable clinical predictors of RAS. In conclusion, RAS is a frequent finding in patients with CAD, particularly when renal insufficiency is also present.