The lumbar vessels in the retroperitoneum must be addressed during many urological and vascular procedures. Few studies have assessed the exact pattern of the lumbar vasculature, and most anatomical descriptions suggest the presence of a generally regular pattern. The number and location of the infrarenal lumbar arteries and veins were documented in 102 consecutive retroperitoneal lymph node dissections. Anomalies of the renal vessels were also noted. The lumbar arteries followed a fairly regular pattern and individual variation occurred mainly in the number of lumbar arteries exiting the aorta (range 2 to 4). Great variation existed among the lumbar veins. The most common pattern of lumbar arteries (60% of the cases) included 3 paired vessels exiting posteriorly at every third of the infrarenal aorta and coursing diagonally toward the lumbar foramina. There was great variation in the number and location of lumbar veins along the inferior vena cava. Commonly 3 lumbar veins entered on the left (44%) and 2 on the right (37%) sides. A lumbar vein entering the left renal vein was documented in 43% of the cases. Accessory renal arteries were found in 24 cases (24%). The number and course of the lumbar vessels are more variable than previously described in the medical literature. Knowledge of these anatomical variations is important for surgeons operating in the retroperitoneum. Several techniques to maintain control of the lumbar vessels are described.