—Anterior pyelotomy was first described by Kapsammer, who claimed that it was not followed by fistula. Rosenstein1 claims that there is no more risk of injuring vessels than by the posterior route. Aberrant vessels, or branches, commonly pass behind the renal pelvis. In some cases the entire upper branch of the renal vein may pass posteriorly to the pelvis. Rosenstein believes that the anterior approach to the kidney is the natural one; the pelvis is reached by retracting or separating the artery and veins. The injury to the kidney is less with this approach than with a posterior incision. A better view is obtained of the pelvis, especially in the obese patient with a short, thick torso, and if there is perinephritis or peripyelitis. There is less hindrance to the outflow of urine following an anterior incision, and the danger of forming a fistula is less.