Because of the retroperitoneal situation of the kidneys, dorsoanterior echography suggests itself. The rapid B-picture process is particularly suitable for urology because the movements of the kidney due to respiration can be followed. "Silent kidney" can be explained. Space-occupying processes can be differentiated. Pararenal processes can be recognised through sonography. Further indications are postoperative monitoring after plastic operations on the efferent urinary passages. The kidney can be visualized without radiation load in allergy to contrast media or in pregnancy. Cyst puncture under echographic observation can contribute to differential diagnosis. Percutaneous nephrostomy under ultrasonic observation can avoid operative intervention.