Thyroid nodules are common and are commonly benign. The reported prevalence of nodularthyroid disease depends on the population studied and the methods used to detect nodules. Noduleincidence increases with age, and is increased in women, in people with iodine deficiency, and afterradiation exposure. Numerous studies suggest a prevalence of 2–6% with palpation, 19–35% withultrasound, and 8–65% in autopsy data. With widespread use of sensitive imaging in clinical practice,incidental thyroid nodules are being discovered with increasing frequency. Ultrasonography is themost accurate and cost-effective method for evaluating and observing thyroid nodules. Currentultrasonography machines are relatively inexpensive, sensitive, and easy to operate. Most endocrinologists are now using ultrasound examination in the initial evaluation of a patient with known orsuspected thyroid nodule. The management of thyroid incidentalomas is a matter of controversy.