Five anterior mediastinal tumors were biopsied with a fine needle under ultrasound guidance. All the tumors were solid, hypoechoic, perivascularly situated masses. Their mean diameter was 7.2 cm. Cytologically there were 2 mediastinal metastatic carcinomas, 1 poorly differentiated carcinoma or non-Hodgkin lymphoma, 1 germ-cell tumor (embryonal cell carcinoma), and 1 malignant lymphoma or thymoma. There were no complications. Ultrasound-guided anterior mediastinal aspiration biopsy is a safe and rapid procedure in the evaluation of anterior mediastinal masses. Biopsy of a mediastinal mass enables simultaneous diagnosis and staging. Mediastinoscopy and diagnostic thoracotomy can be avoided.