BACKGROUND : There has been recent interest in identifying the endoscopic ultrasonographic characteristics of lymph nodes (LNs) that predict the presence or absence of malignant involvement. Normal LN anatomy includes the presence of a central intranodal blood vessel (CIV) that can be obliterated with invasion of malignant cells. We sought to determine whether examining LNs for the presence or absence of a CIV during endobronchial ultrasound (EBUS) could predict benign or malignant cytology of the samples obtained. METHODS : We prospectively evaluated patients undergoing EBUS-transbronchial needle aspiration (TBNA) for mediastinal or hilar adenopathy in a tertiary care referral center. All LNs were prospectively characterized as having or not having a CIV and subsequently classified as benign or malignant by cytologic analysis. RESULTS : A total of 56 patients undergoing EBUS-TBNA were evaluated. One hundred three LNs were available for analysis. Fifty-six of 103 LNs were positive for malignancy (54.3%). Ultrasonographic identification of a CIV was associated with benign LN cytology with a sensitivity of 83.0% and a specificity of 91.1% and an OR of 49.7 (95% confidence interval, 15.1-163.9). Finding a CIV had a positive predictive value for benign LN cytology of 88.6%. The absence of finding a CIV had a positive predictive value for malignant cytology of 86.4%. The presence or absence of a CIV had an overall diagnostic accuracy of 87.4% (correctly categorizing 90 of 103 LNs). CONCLUSIONS : There are morphologic characteristics of LNs that can be visualized at the time of EBUS to help predict whether the nodes being evaluated have malignant involvement. The presence of a CIV suggests that the node is benign, whereas the absence of a central intranodal vessel increases the likelihood of malignancy. The presence or absence of a CIV has a good overall accuracy in predicting malignancy (87.4%).