BACKGROUND: Free-breathing expiration-gating (EG) is a non-invasive technique used to manage respiratory-induced tumor motion. This study explores the effectiveness of EG stereotactic body radiotherapy (SBRT) for lung tumors using 10MV FFF VMAT. METHODS AND MATERIALS: The study included 41 patients (50 targets) treated with EG lung SBRT between September 2019 and February 2023. Patients underwent free-breathing uncoached 10-phase 4DCT for planning, with the choice for EG based on e.g. tumor motion, critical organ dose, expected target visibility on free-breathing CBCT, taking into account suitability of the breathing pattern. The gating window was typically set at phases 30-70 % of the breathing cycle. Treatment planning utilized VMAT with 10MV FFF, and tumor motion was monitored using EG-CBCT ± near real-time markerless kV imaging. Treatment times for the different parts of treatment, tumor stability and clinical outcomes were evaluated. Dosimetric outcomes were compared between EG and free-breathing plans for a subset of 10 patients. RESULTS: EG SBRT substantially reduced longitudinal tumor motion and internal target volume (ITV) by 77 % and 42 % respectively. There was a mean decrease of 21/24 % in V5/V20Gy for the ipsilateral lung. Motion monitoring during treatment for 20 targets showed that intrafraction tumor motion remained within 2 mm for most patients, ensuring accurate dose delivery. 86 % of fractions were completed within 25 min. No local recurrences were observed during a median follow-up of 13 months. CONCLUSION: Free-breathing EG SBRT is a feasible, effective, and practical approach for lung cancer treatment, offering significant reductions in tumor motion and lung doses while maintaining high treatment accuracy and acceptable treatment times.