BACKGROUND. Endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) biopsy allows the detailed imaging and FNA not only of both intramural and extramural structures and lesions of the gastrointestinal (GI) tract but also of various intraabdominal organs. Thus, EUS-FNA biopsy offers a novel opportunity to evaluate and obtain cytology samples from adrenal gland lesions. The objective of the current study was to determine the utility of EUS-FNA in the diagnosis of adrenal lesions. METHODS. The authors conducted a prospective evaluation of 24 consecutive EUS-FNA biopsy specimens obtained from patients with adrenal lesions. An attending cytopathologist was present on site to assess specimen adequacy and to provide rapid interpretation of air-dried material that had been stained with Diff-Quik (Baxter Scientific Products, McGraw Park, IL). Additional samples were obtained for ThinPrep (Cytyc Corporation, Boxborough, MA) preparation, and cell blocks subsequently were prepared. Appropriate immunohistochemical staining was performed as indicated. The cytologic diagnosis was then analyzed for correlations with the final diagnosis, which was based on relevant correlative cytologic or histologic examination of biopsied/resected pathology materials and/or final clinical follow-up. RESULTS. In total, 24 EUS-FNA biopsy specimens (from 18 males and 6 females) were obtained from adrenal glands. The mean patient age was 62.2 years (range, 48-81 years). Adequate cellularity was noted in all 24 samples. Seven of 24 samples (29%) were reported to be positive for carcinoma. All samples that were diagnosed as metastatic carcinoma were confirmed on subsequent follow-up. EUS-FNA performed simultaneously with adrenal gland aspiration either from the primary site (n = 1) or from metastases to lymph nodes (n = 3) supported diagnoses of metastatic carcinoma. Six of seven samples were metastatic from the lung, and one specimen was a direct extension of a transitional renal cell carcinoma. EUS-FNA biopsy of the right adrenal gland in one patient revealed myelolipoma. In 16 patients, benign adrenal gland cells were noted on EUS-FNA biopsy specimens from enlarged adrenal glands. In 5 samples (31%), signs of adenoma were evident. Morphology alone could not distinguish between adrenal adenoma and adrenal hyperplasia. No significant complications were reported after EUS-FNA biopsy of adrenal glands. CONCLUSIONS. EUS-FNA biopsy is a highly specific and safe technique for confirming the diagnosis of carcinoma metastatic to the adrenal glands. Along with cytologic evaluation, EUS imaging is needed to support the diagnosis of adrenal adenoma. © 2004 American Cancer Society.