Diagnosis of renal artery stenosis (RAS) should be discussed in numerous clinical situations including refractory high blood pressure (HBP), HBP in a polyvascular patient, degradation of renal function following renin angiotensin inhibitor or flash pulmonary edema. Ultrasound-doppler coupled with gadolinium-enhanced MR or CT angiography has proven adequate for most patients with RAS. Digital subtraction angiography should be limited to revascularisation procedures. Functional testing are not sensitive or specific enough because the degree of renin activation differs widely among patients with RAS. Renal percutaneous angioplasty induces a light to moderate decrease in blood pressure, has no effect on renal function but allows to reduce the number of anti-hypertensive drugs. Stenting completed angioplasty is worthwhile in most patients with atherosclerotic RAS. ACE inhibitors decrease mortality and increase renal function in patients with RAS.