Abstract: Objective To investigate the expression levels and clinical significance of long noncoding RNA lncRNA-activated by TGF-β（lncRNA-ATB） in tissues and sera of lung adenocarcinoma. Methods In this study， preoperative serum specimen and surgical resected cancer tissue together with paired adjacent tissue samples were collected from 82 patients with lung adenocarcinoma. The serum samples of 65 healthy subjects were selected as the control group. LncRNA-ATB levels were detected by real-time quantitative RT-PCR （qRT-PCR） method. The relationship between tissue/serum levels of lncRNA-ATB and clinical pathological parameters （gender， age， TNM stage， tumor size， degree of differentiation， lymph node metastasis and CEA level） were analyzed. The receiver operating characteristic curve （ROC） was employed to evaluate the efficiency of tissue/serum levels of lncRNA-ATB in diagnosis of lung adenocarcinoma from healthy. Results There were higher levels of lncRNA-ATB in both tissues and sera of lung adenocarcinoma as compared with their controls （P＜0.05）. The serum level of lncRNA-ATB was positively correlated with its tissue level （r=0.642， P＜0.05）. The expression of lncRNA-ATB in lung adenocarcinoma tissues and sera were related to TNM stage， tumor size and lymph node metastasis. The value of tissue and plasma levels of lncRNA-ATB for the diagnosis of lung adenocarcinoma was better with a higher area-under-the-curve and sensitivity than CEA. Conclusion There were higher levels of LncRNA-ATB in both tissues and sera of lung adenocarcinoma. Levels of LncRNA-ATB were related with TNM stage， tumor size and lymph node metastasis， probably playing a role in development of lung adenocarcinoma. Serum lncRNA-ATB has a higher value in the early diagnosis of lung cancer， worthing of clinical application.