Objective <p>To compare the efficacy and safety of 95% ethanol rinse combined with lauromacrogol injection versus lauromacrogol injection alone in sclerotherapy for simple renal cysts in elderly patients.</p> Methods <p>This retrospective analysis included 94 patients (63 males, 31 females; mean age, 70.15 years) with symptomatic simple renal cysts who underwent ultrasound-guided percutaneous sclerotherapy between 2019 and 2025. Forty-eight patients received lauromacrogol injection alone, while 46 patients received 95% ethanol rinse combined with lauromacrogol injection. All patients were followed up at 1, 6, and 12 months after the procedure.</p> Results <p>The volume of simple renal cysts decreased during follow-up, from a mean initial volume of 113.2 mL to a final volume of 0.30 mL. At 12 months, the total resolution rate was 98.9% (93/94), and the cure rate was 97.9% (92/94). No significant differences were observed between the two groups in volume reduction rate, resolution rate, or cure rate during follow-up (all <i>P</i> &gt; 0.05). The adverse event rate was significantly higher in the ethanol-combination group than in the lauromacrogol-monotherapy group (56.5% [26/46] vs. 29.2% [14/48]; <i>P</i> &lt; 0.05). Ethanol use was associated with significantly more pain and a higher incidence of fever, even when limited to rinsing the cyst lumen prior to lauromacrogol injection.</p> Conclusion <p>Percutaneous sclerotherapy was successful in both groups of elderly patients with simple renal cysts. Lauromacrogol injection alone was associated with a significantly lower incidence of minor adverse events.</p> Clinical trial number <p>Not applicable.</p>