INTRODUCTION: Vapor-Tunnel™ (VT) consists of a very long pulse that uses the minimum peak power, causing the energy to pass through a previously created vapor channel or tunnel. There are studies that have shown acceptable ablation lithotripsy efficiency. Nevertheless, there are no in-vivo studies that have compared the VT performance according to the stone density. METHODS: A retrospective study of 152 patients who underwent RIRS using VT Ho:YAG laser was performed. We divided the patients according to the stone density (Group 1: <
1000UH vs. Group 2: >
1000UH). We assessed the lithotripsy efficiency (mm RESULTS: Ninety three patients were included in Group 1 and 59 in Group 2. Body mass index was higher in Group 1 and the median stone volume was higher in Group 2 (846 vs. 672 mm CONCLUSIONS: VT Ho:YAG was associated with decreased laser time, operative time and laser-energy consumption in Group 1 than Group 2. Similarly, VT Ho:YAG increased lithotripsy efficiency and the SFR compared to hard stones with the same laser settings and pulse modality.