Background and purpose: Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) is a new minimally invasive method in the dignosis for mediastinal lymph nodes. This study was to evaluate the diagnostic yield of EBUS-TBNA for mediastinal lymph nodes. Methods: Twenty patients with mediastinal lymph nodes found by CT underwent the dignosis by EBUS-TBNA form April 1st 2009 to July 16th 2009. The sensitivity, specificity, positive predictive value, negative predictive value and diagnostic accuracy of EBUS-TBNA were evaluated. Results: Twenty patients with 37 lymph node groups were studied. Overall sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy of EBUS-TBNA for diagnostic were 84.62%, 100%, 100%, 77.78% and 90.00%, respectively. The diagnostic accuracy for cancer was 100%. The operation time was 11.9min per group in average with no serious complication. The median length of hospital stay was 1 (range from 1 to 17 days) day after operation. There were significant differences in the average operation time between the first three patients and the others (36.25 min vs. 7.76 min; z=3.247, P=0.001). Conclusion: Endobronchial ultrasound-guided transbronchial needle aspiration proved to be a safe procedure with a high yield for the diagnosis of mediastinal lymph nodes.