INTRODUCTION: Lung cancer in the transplanted organ is an extremely rare occurrence with very few cases reported. The use of stereotactic body radiotherapy (SBRT) for medically inoperable early stage non-small cell lung cancer is an option to treat an early stage lung adenocarcinoma on a transplanted lung. CASE PRESENTATION: We report the case of a 63-year-old woman with a history of hypersensitivity pneumonitis, who underwent a right lung transplant in 2010 and developed pulmonary adenocarcinoma, stage IA2, in 2023. The patient was ineligible for surgical management and was referred for SBRT. The treatment was administered with a total dose of 48 Gy in 4 fractions in December 2023. The nodule remained stable at 9-month follow-up, with post-radiogenic pneumonitis observed. Pulmonary function remained stable after treatment. CONCLUSIONS: This case shows that SBRT on a transplanted lung cancer seems to be safe, even maintaining a standard SBRT fractionation, with good early local control. Careful consideration of dose, fractionation, and potential toxicities is essential in managing these complex cases, always in close cooperation with the transplant medical team.