The contribution of radio surgery (RGS) using octreotide labeled with Indium-111 (In111) has been studied for surgical treatment of lung cancer. Thirteen patients were administered 111 Mbq of In111 octreotide intravenously. Scintigraphic images were preoperatively taken at 4, 24, and 48 hours after the tracer injection. Pulmonary resection and intraoperative evaluation by RGS technique were then performed to set the section limits. Histological staining of all the resected specimens and resection margins were assessed and their results were used as a confirmation of the RGS intraoperative findings. RGS is a simple method that can help the surgeon in the intraoperative assessment of bronchial, parenchymal, and parietal resection margins. Further research is needed to verify whether this method also may be useful in the intraoperative definition of the extent of mediastinal lymph node dissection.