Percutaneous puncture ethanol sclerotherapy is a simple, effective, minimally invasive, and inexpensive procedure to manage symptomatic simple renal cysts. We modified specific technical aspects to balance certain potential intraprocedural factors for ensuring minimal procedural pain and duration as well as maximal clinical therapeutic effects and evaluated the safety and efficacy of this modified technique. A total of 84 eligible patients underwent computed tomography-guided single-session ethanol sclerotherapy using the conventional (group A) or modified (group B) technique. In group B, the puncture route was modified from tansparenchymal to direct for reducing renal injury, and preinjection of low-dose intracystic lidocaine was used to control distending pain caused by ethanol injections; therefore, greater ethanol volumes could be injected for improving the resistance and contact of ethanol with the cyst wall, precluding the need for patient repositioning multiple times to decrease procedural duration. Visual analog scale score for pain and procedural time were significantly higher in group A than in group B. The complication rate was slightly higher in group A than in group B, but the success rate was comparable between the two groups. These results suggest that the modified technique is painless, time-saving, and injury-reducing and can thus improve medical care.Simple renal cysts (SRCs) are one of the most commonly acquired renal cystic diseases and are frequent in the elderly given that their prevalence increases with age 1 . Symptomatic SRCs present common clinical symptoms such as flank pain or mass, hypertension, and hydronephrosis. Percutaneous ethanol sclerotherapy is a simple, effective, minimally invasive, and inexpensive treatment for symptomatic SRCs 2 . Therefore, it is often the first-line procedure and is widely used in clinical practice; however, the procedure has not been standardized to date 3 . The conventional technique reported by Xu et al. 4 is used in early stages of the disease, and its advantages include the use of three-way drainage tube, which prevents air from entering the cyst, and of high ethanol concentration over repeated cycles of injection-suction, which eliminate the step of ethanol dilution 4 . Moreover, fragments of protein-denatured substances are removed to allow a directly contact between ethanol and epithelial lining of the cyst wall. The computed tomography (CT) value is used to monitor ethanol concentration for improving treatment efficacy 4,5 , which is based on the linear correlation between ethanol concentration/density and CT attenuation; when the CT value is lower than −190 HU, ethanol concentration is considered to be greater than 90%.However, we have encountered a few problems in the course of our clinical practice. First, this puncture route can damage renal tissues, thus increasing the risk of intracystic hemorrhage and hematuria 6 . Second, patients complain of distending pain caused by ethanol injections 7 . Third, the patient's position needs to be chan...