Forty-two fine-needle aspirates (FNA) of the mediastinum were reviewed from 1984-1995. The clinical, radiologic, pathologic, and cytologic material was studied. Twenty-five males and 17 females had an age range from 10-72 yr and a mean of 41 yr. Common complaints were chest pain, dyspnea, and cough. Thirty-eight tumors were in the anterior/superior mediastinum. Fifty-seven percent were primary neoplasms (Hodgkin's lymphoma, 7; non-Hodgkin's lymphoma, 6; thymoma, 3; germ-cell tumor, 3; thymic carcinoid and angiosarcoma, 1 each; and malignant not otherwise specified, 3). Twenty-four percent were metastatic tumors (carcinoma, 9; and sarcoma, 1). Twelve percent were benign conditions (granulomatous disease, 2; multinodular goiter, 1; extramedullary hematopoesis, 1; and one thymic cyst). Seven percent were inconclusive. FNA yielded adequate tissue for diagnosis in 83% and a correct diagnosis in 86%. There was one false-negative and no false-positive diagnosis. FNA is a useful tool for accurate tissue diagnosis of mediastinal masses.