Organ preservation by renal surgery is the principal and most pressing task of urology, according to Bischoff. In clinical practice at the present time, resection of the renal parenchyma is the principal aim and is to a large extent achieved. Sacrificing a localised diseased portion of the parenchyma (organ amputation) contributes to the survival of the rest of the organ (preservation of the organ). The additional inevitable loss of functional tissue must be kept as small as possible (sparing the organ). Decisive syndromes are nephrolithiasis, renal tumors and to a decreasing extent, tuberculosis of the urinary system. The operation, which usually takes the form of resection of the pole of the kidney, but which must sometimes be extended to heminephrectomy and even more, repeatedly underlies attempts at improvement both in animal experiments and in the clinical sphere.