A review of 52 consecutive needle biopsies of the mediastinum is presented. The aspirated material yielded cytologic and/or histologic diagnosis in 50 needle biopsies; two needle biopsies failed to yield adequate cellular material for diagnosis. All but two of the 50 patients had confirmation of the biopsy diagnosis by surgical, autopsy, or clinical correlation. In 32 patients, a 20-gauge needle was used for the biopsy. A larger-bore (17-gauge) needle with a cutting device was used in 20 cases to obtain more tissue for histologic diagnosis of benign or unusual malignant lesions. Despite the larger size of the needle, the rate of complications remained low.