Vast majority of the popoulation has one renal artery for each kidney, as described in almost every atlas of human anatomy, which divides into two or more branches at hilum. This pattern isn´t free of variations. Double or triple renal arteries have been described, so as polar arteries with aortic, iliac or even mesenteric origins. There is an incidence of 20-50% for multiple renal arteries.

These anatomical variants are explained by renal embriology. The kidneys begin their embryogenesis at pelvis, appearing for the first time at fifth week of pregnancy, and they have vascular supply from pelvic branches. Then, they ascend proressively towards the abdomen triggering the development of new branches arrising from aorta. So that, the kidneys are being supplied by highest arterial branches until they reach normal anatomical position;otherwise lowest branches progressively degenerate. As result, vascular variants are consequence of embrionary vessels that usually disappear when definitive renal artery is formed.

Both renal arteries tipycally arise at L2 level from aorta, just below superior mesenteric origin. Right artery origin arises usually superior and anterolateral to the origino f left renal artery. Main renal arteries branch into anterior and posterior divisions. Anterior division subdivide into four segmentary branches which include: anterior-superior, upper, middle and lower branches. Posterior division subdivides into posterior segmentary branches, and supplies less renal parenchyma than anterior division branches. (FIGURE 1). Segmentary arteries divide into lobar branches, and this ones subdivide into arcuate arteries.

Inferior adrenal branches, capsular branches, and proximal ureter or renal pelvic branches also depend on main renal arteries.