Abstract: Objective:To evaluate the efficacy and safety of fractionated stereotactic radiotherapy(FSRT) in the treatment of lung metastatic tumors.Methods:Thirty-one cases(1 to 3 lesions each case) were treated with FSRT.Single target dose of surrounding area was from 3 to 5 Gy,which total radiation dose was from 30 to 45Gy through 7 to 9 times completing.The 50% of dosage curve covered the planning target volume.Results:Up to Dec.2011,25 patients died.The median overall survival was 20.7 months(3.5 to 42.9 months),the overall survival rates of 1 year and 2 years were 78.4% and 43.2%,respectively.The clinical symptoms remission and local tumor control rates of all patients were 84.1% and 90.4%,respectively.The differences of the survival rate of patients with pulmonary lesions and no pulmonary lesions were significant(P=0.043).The effective rates of squamous carcinoma and adenocarcinoma were 83.3%(10/12) and 85.7%(12/14),respectively.The effective rates of cancer derived from epithelium and no epithelium were 84.6% and 3/3,respectively,which differences were not significant(P=1.000).Conclusions:FSRT in the treatment of lung metastasis is effective and safe,which can prolong the survival under strict mastering indications.The prognosis of patient with single and no pulmonary metastasis is good.