PURPOSE: The purpose of this study was to evaluate the effectiveness of percutaneous fine-needle aspiration (PCNA) in malignant and benign mediastinal lesions. MATERIALS AND METHODS: PCNA of mediastinal lesions were performed in 46 patients using 22 Guage thin-walled Westcott type needle under fluoroscopy guidance. There were 24 malignant mediastinal masses, 18 of which were diagnosed only by PCNA and six of which were proven surgically. Of 22 benign mediastinal masses, 19 cases were proven surgically. RESULTS: In 24 patients with malignant neoplasms, a positive diagnosis of malignancy was established in 18 (75%). One suspicious malignancy and five false negative results occurred. In 22 patients with benign masses, a specific diagnosis was established in six (27.3%), and 13 patients revealed nonspecific benignanay (59.1%). Three benign masses were reported as unsatisfactory. Five patients developed pneumothorax as a complication, and one of these needed a chest tube. CONCLUSION: Percutaneous fine-needle aspiration in mediastinal masses can differentiate benign mass from malignancy and can make a pathologic diagnosis.