Renal artery stenosis (RAS) is a particularly relevant co morbid condition in cardiological practice, since the risk factors for coronary artery disease (CAD) and renal artery disease are identical. Consequently both vascular beds are commonly affected by atherosclerosis in the same patient.The prevalence of renal artery stenosis in general population is poorly defined because of no availability of a simple and reliable screening test. In Egypt, There is insufficient data concerning the incidence of RAS in general population and especially in patients with CAD.The aim of this study was:1.To determine the incidence of RAS in patients with suspected CAD and who were undergoing coronary angiography.2.To determine the risk factors and predictors of RAS.We studied 120 patients with clinical and/or ECG evidence of CAD (65 males and 55 females) with a mean age 54.59 + 9 years (mean + SD) ranging from 33 to 85 years. Risk factors included smoking in 35%, diabetes mellitus in 39% and hypertension in 58%.Following admission, all patients were subjected to clinical evaluation, twelve lead ECG and routine laboratory study prior to diagnostic angiography. Twenty six patients (21.6%) had renal function impairment i.e. serum Cr level > 1.3 mg/dl.Coronary angiograms were analyzed for the presence, extent and severity of CAD and selective renal angiography was performed with end of the procedure.Out of the 120 patients studied, 81 (67.5%) showed angiographic evidence of CAD (group A) whereas 39 (32.5%) had normal coronary artery (group B).Out of the 81 patients with CAD, 23 (28.4%) exhibited angiographic evidence of RAS versus only 2 patients out of the 39 with normal coronary arteries (5.1%) had RAS, of the later group, only one patient (2.56%) had significant RAS i.e. >50% luminal stenosis vs. 14 patients (17.28%) out of the 23 of group A.Group A patients with CAD exhibited higher prevalence of RAS with 3 vessel disease than single or two vessel disease (36.7% vs. 15.6 %, p<0.029).Compared to patients without RAS, those with RAS had significantly older age (59.28+8.54 for the RAS group vs. 53.36+8.94 in the non RAS group, p < 0.05), higher prevalence of hypertension (84 vs. 51%, p < 0.003), significantly more hyperlipidemia (64% in RAS group vs. 29.5% in the NRAS group, p< 0.001), and hypokalemia (20% in the RAS group vs. 4.2% in the NRAS group, p< 0.008).In conclusion, renal angiography unmasks unsuspected RAS in patients with clinically suspected CAD. RAS is present in up to 20% of patients with CAD particularly those with 3 vessel affection. Prevalence of RAS is significantly relates to old age, hypertension and hyperlipidemia but not to sex, smoking or diabetes mellitus. Qualitative renal angiography should be routinely done during diagnostic coronary angiography and correlated with the clinical presentation and therapeutic plan.