A 52-year-old woman was evaluated for an enlarging neck mass. Fine-needle aspirate contained Hürthle cells and thyroidectomy revealed two separate thyroid morphologically similar lesions. Immunohistochemical studies confirmed diagnoses of separate Hürthle cell thyroid and oxyphil parathyroid adenomas. Diagnostic pitfalls and the role of immunohistochemistry in diagnosis are discussed. © 1994 John Wiley & Sons, Inc.