Several procedures are available for the cytopathological diagnosis of mediastinal lesions. The purpose of this study was to evaluate the diagnostic value of endoscopic ultrasonography (EUS)-guided fine-needle aspiration (FNA) in patients with mediastinal mass lesions/lymph node enlargement. All patients had intrapulmonary lesions on chest X ray and/or CT scan, and inconclusive findings by endobronchial forceps biopsy and/or brush cytology. EUS-guided FNA was performed in 16 patients using a modified oblique forward-viewing gastroscope with an electronic multielement curved linear ultrasound transducer. After the region of interest was localized, a 22-gauge Vilmann-Hancke needle was introduced via the 2-mm biopsy channel. The cytological diagnosis of EUS-guided FNA was conclusive for cancer in 9 patients and in the other 7 patients the aspirated samples revealed a benign lesion. In 10 patients the final diagnosis was cancer, thus EUS-guided FNA was diagnostic for malignancy in all but 1 of the lesions (sensitivity 90.0%). In 1 patient epitheloid cell granuloma was detected by cytological examination of the FNA. Following tuberculostatic treatment the lesions disappeared completely on CT scan and EUS. The overall accuracy in this study amounted to 93.7%. From this and other studies discussed, it is assumed that the procedure is an accurate and safe technique to examine nodular lesions suggestive of metastatic lymph node involvement.