RESUMEN
The retroperitoneal lumbar vessels should be immediately recognized during urological, vascular and radiologicalmedical procedures. Few studies have tried to define an exact pattern for the lumbar vasculature andmost of the anatomical descriptions suggest the presence of a regular pattern. Nevertheless, for the renal bloodvessels, despite the described regular pattern, several anatomical variations have interested anatomists for morethan a century. Taking into account that there is a constant need for reviewing this anatomy due to the advancesin surgical and/or uroradiological procedures techniques, we describe a complex variation of the renalblood vessels found during the dissection routine in our laboratory. A male cadaver, aged 65 years, embalmedwith 10% formalin solution presented, on the left side, two renal arteries arising from the abdominal aorta,both of them entering the kidney on the hilar region. From the hilar region of the left kidney, there were alsotwo tributary renal veins, which join together 3.0 cm from the hilus, before draining into the inferior venacava. These two tributary veins were large in diameter, and made a loop around the two renal arteries and alsothe ureter. No anatomical variations were found on the right side. This is a complex anatomical variation of therenal vessels which might have functional implications once the venous loop described might be a compressionfactor for the renal arteries and for the ureter.