The authors review 41 recent articles concerning the diagnosis and treatment of thyroid, adrenal, and thymic tumors. Diagnostic and evaluative techniques for thyroid nodules are inexact; fine-needle aspiration cytology offers the best results. Most authors favor total thyroidectomy and postoperative 131I ablation. The issue of elective versus therapeutic cervical lymphoidectomy remains controversial. Chemotherapy is of very little use in treating differentiated thyroid carcinoma. The most useful follow-up technique is whole-body scanning in conjunction with thyroglobulin determination. Persistent hypercalcitoninemia after surgery for medullary thyroid carcinoma is not uncommon and does not necessarily indicate demonstrably recurrent disease. In imaging adrenal tumors, magnetic resonance imaging appears to have some advantages over computed tomography. Pheochromocytomas may not always present classically; a clear understanding of the biochemical diagnosis is essential. Patients with thymomas have a good prognosis. Surgical treatment of encapsulated thymomas is appropriate, although more extensive thymomas are best treated multimodally.