Purpose. Comparison of the long-term outcomes of the treatment of simple liver cysts by traditional and modified RFA methods.Materials and methods. From 2015 to 2018, US-guided RF ablation was used to treat simple nonparasitic hepatic cysts in 14 patients. There were 15 operated cysts in total. 7 patients of group A underwent standard RFA session without temperature restrictions. 7 patients of group B with localization of cysts closely to large vessels and bile ducts or the area of portal fissure, underwent RFA at 60 °C with preinjection of 10% NaCl solution into the cyst cavity. During the intervention, the temperature of the surrounding electrode tissue and the exposure time were recorded.Results. All patients underwent interventions satisfactorily; no complications were observed. In group A, the mean cyst diameter was 50.3 ± 15.2 mm, and the mean initial cyst volume was 77.09 ± 23.2 cm3. In group B, the mean cyst diameter was 61.8 ± 14.9 mm, and the mean initial cyst volume was 137.8 ± 39.2 cm3. After 3 months, the overall decrease in the volume of operated cysts on CT was in group A – 27.1%, in group B – 50.6%; after 6 months – 49.8% and 60.4%, respectively. After 12 months, similar indicators in group A amounted to 64.2%, in group B – 79.2%. 1.5 years after surgery, the volume of operated cysts in group A decreased by 65.2%, in group B by 91.2%; and after 2 years – by 68.9% and 93.6%, respectively. The total decrease of cyst volume at the last control in group B was 24.7% more than in group A. The decrease in cyst volume by more than 50% was noted in group A in 37.5%, in group B – in 85.7%. Complete reduction of the cyst cavity was noted in group A in 25%, in group B in 28.5%. The difference in the decrease of the cyst volumes between the groups after 2 years is statistically significant (p = 0.03), thus it can be concluded that a significantly more pronounced decrease in cyst volumes was observed in group B than in group A.Conclusion. Preinjection into the cystic cavity of a 10% solution of NaCl allowed to achieve a more pronounced decrease of the cystic cavities with the lower RFA temperature regime. At a temperature of 60 °C, the thermal damage minimally spreads to adjacent healthy liver tissue andis sufficient for the radical treatment of the cystic cavity. This makes possible to use the modified RFA method for cysts, located close to the large vessels and bile ducts.