Small pulmonary nodules in patients with sarcoma are problematic, because it is difficult to distinguish such small metastatic nodules from benign. The purpose of this study was to establish management guidelines for such small pulmonary nodules in patients with sarcoma. Pulmonary nodules were detected in 70 of 206 patients with sarcoma. About 55 patients were classified as having pulmonary metastasis. Seventeen of these 55 patients with pulmonary metastases were excluded from the imaging review because they did not undergo the required imaging examination. This study reviewed 38 patients with metastatic nodules and 15 patients with benign nodules. A statistically significant relationship was observed between the size of the nodules and final clinical decision. The patients with pulmonary nodules which did not exceed 5 mm in size showed significantly better cumulative overall survival rate after the detection of pulmonary nodules than those with larger nodules (5-years: 58.4 vs. 20.4%). There was no significant difference in the overall survival rate between the patients with smaller pulmonary benign lesions which did not exceed 5 mm in size and those with a normal chest CT (5-years: 92.3 vs. 85.3%). The only factor to diagnose in a metastatic pulmonary lesion is the size of the nodules. If the nodule remains < or = 5 mm in size for more than 6 months, the nodule will be a benign lesion. On the contrary, if the nodule becomes larger than 5 mm within 6 months, a surgical excision of the nodules is recommended.