Ultrasound (US)-guided puncture and alcoholization are the gold standard technique for the treatment of simple renal cysts. The main indications for the treatment of simple cysts are pain due to the mass compression effect, obstruction of the excretory tract, arterial hypertension, and patient anxiety. In addition, it is preferable to treat all renal cysts with a longitudinal diameter of 9 cm or more. The treatment method consists of the insertion of a sclerosing substance inside the cyst cavity, after having emptied it under US guidance. The aim is to sclerose the cyst walls so as to reduce the risk of recurrence. The treatment can be repeated two or three times, but in many experiences, a single treatment was sufficient to guarantee comparable results to multiple sclerosing sessions. The success of the treatment seems to depend on how long the ethyl alcohol remains in contact with the cyst walls. There is a negligible incidence of complications, so the method can be considered safe and reliable.