Background: Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) is necessary to evaluate suspicious lymph node involvement of lung cancer because computed tomography (CT) or positron emission tomography (PET-CT) have limitations in its low sensitivity and specificity. There are several benign reasons that can cause false positive lymph node such as anthracofibrosis, old or active tuberculosis or other infectious conditions. Objective: The purpose of this study was to evaluate possible causes of false positive lymph node by CT or PET-CT. Methods: Two hundred forty-seven patients who were initially diagnosed with lung cancer between May 2009 and December 2012, and underwent EBUS-TBNA for confirmation of suspicious lymph node involvement by CT or PET-CT were analyzed in the study. Results: Bronchial anthracofibrosis, old or active tuberculosis, infection such as pneumonia tended to be related with negative lymph node involvement by EBUS-TBNA, but statistically insignificant. However, there was positive relation to false positive lymph node involvement with increased age. Conclusion: These findings suggest that lung cancer staging should be done more carefully when a patient has clinically benign lymph node characteristics.Background: Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) is necessary to evaluate suspicious lymph node involvement of lung cancer because computed tomography (CT) or positron emission tomography (PET-CT) have limitations in its low sensitivity and specificity. There are several benign reasons that can cause false positive lymph node such as anthracofibrosis, old or active tuberculosis or other infectious conditions. Objective: The purpose of this study was to evaluate possible causes of false positive lymph node by CT or PET-CT. Methods: Two hundred forty-seven patients who were initially diagnosed with lung cancer between May 2009 and December 2012, and underwent EBUS-TBNA for confirmation of suspicious lymph node involvement by CT or PET-CT were analyzed in the study. Results: Bronchial anthracofibrosis, old or active tuberculosis, infection such as pneumonia tended to be related with negative lymph node involvement by EBUS-TBNA, but statistically insignificant. However, there was positive relation to false positive lymph node involvement with increased age. Conclusion: These findings suggest that lung cancer staging should be done more carefully when a patient has clinically benign lymph node characteristics.