This chapter focuses on renal vascular diseases defined as stenosis or occlusion of one or more main renal arteries, which may be unilateral or bilateral. Hemodynamically relevant renal artery stenosis (RAS) may lead to renovascular hypertension, ischemic nephropathy, and eventually serve as a culprit for cardiorenal syndromes, including flush pulmonary edema [1]. The most common nature of RAS is atherosclerotic disease of the proximal part of the main renal artery, and the remaining are mainly caused by underlying fibromuscular dysplasia (FMD), typically affecting the midportion or distal segments of the renal artery [2]. However, there are also some other rare causes leading to renovascular hypertension. The epidemiology and different etiologies of renal vascular diseases, their pathophysiology and clinical presentation, as well as the systematic diagnostic approach using a variety of different imaging modalities are summerized in this chapter. The therapeutic aspects of RAS, particularly treatment performing endovascular interventional techniques in the renal artery (PTRA) and the patient selection for revascularization, are discussed in a separate chapter.