The right renal vein, along with the left renal vein, makes up the renal veins that drain the kidneys. They attach the inferior vena cava to the kidney. The right renal vein is smaller than the left. It begins at the hilum of the kidney where three to six tributaries meet. These veins are behind the renal arteries. This goes against most other relationships between veins and arteries in the abdomen. Most veins are behind or with the arteries. The right renal vein drains straight into the inferior vena cava.