ObjectiveTo evaluate the efficacy, feasibility and safety of CT guided percutaneous 125Ⅰ seeds implantation in elderly patients of stage Ⅰperipheral non-small cell lung cancer ( NSCLC ).MethodsClinical data of 16 elderly peripheral stage Ⅰ NSCLC patients ( 10 squamous carcinoma and 6adenocarcinoma;13 stage ⅠA and 3 stage ⅠB ) who received radioactive 125Ⅰ seeds implantation because of refusal or being unsuited to operation or external radiotherapy were retrospectively analyzed. Prescribed dose was 140 - 160 Gy. Under CT guidance, 125Ⅰ seeds were implanted percutaneously into tumors for interstitial radiotherapy according to treatment plan system. ResultsMean number of 125Ⅰ seeds each patient received was21.1. 12 complete response (CR) and 4 partial response (PR) were achieved. Total response rate ( CR + PR) was 100％. 100％ patients completed 10 to 56 months of follow-up, 15, 13, 8 and 6 patients completed 1-, 2-, 3-and 4-years'follow-up, respectively. The median local progression free time was 14months. The 1-,2-,3-and 4-year overall survival rate were 60％, 54％, 50％ and 33％, respectively (median:14 months). 7 cases died of non-tumor disease and 5 died of metastasis. No severe complications were observed. ConclusionsCT guided 125Ⅰ seeds implantation is a safe, reliable and effective radical treatment method for elderly stage Ⅰ peripheral NSCLC patients, who refuse to or are unsuitable to operation or external radiotherapy.