Background: The purpose of this study was to re-evaluate echo features of lymph nodes during endoscopic ultrasound and assess the utility of these echo features and endoscopic ultrasound–guided fine-needle aspiration in predicting malignant lymph node invasion. Methods: Thirty-five lymph nodes in 25 patients with lung, esophageal, and pancreatic cancer were evaluated by endoscopic ultrasound. Endoscopic ultrasound examinations were performed with a radial scanning echoendoscope. Confirmation of benign lymph nodes was obtained by surgical resection while malignant lymph nodes were confirmed by real-time endoscopic ultrasound–guided fine-needle aspiration with a linear array echoendoscope. Results: Nineteen benign lymph nodes and 16 malignant lymph nodes in the mediastinum, celiac axis, and the peripancreatic area were included in the study. The following echo features were compared between benign and malignant lymph nodes: size greater than 1 cm, hypoechoic, distinct margins, and round shape. No single feature independently predicted malignant invasion. When all four of the above features were present in the same lymph node, the accuracy for predicting malignant invasion was 80%. However, all four features of malignant involvement were present in only 25% (4 of 16) of malignant lymph nodes. Our study also suggests that the above echo features may be a less reliable predictor of malignant invasion in pulmonary malignancies when compared to gastrointestinal cancers. Endoscopic ultrasound–guided fine-needle aspiration of lymph nodes in 22 patients revealed malignant lymph node invasion in 16 and benign cells in 6 patients. Conclusion: Endoscopic ultrasound–guided fine-needle aspiration is an important adjunct for accurate lymph node assessment for malignancy. (Gastrointest Endosc 1997;45:474-9.)