Thyroid nodules are common and are commonly benign. The reported prevalence of nodular thyroid disease depends on the population studied and the methods used to detect nodules. Nodule incidence increases with age, and is increased in women, in people with iodine deficiency, and after radiation exposure. Numerous studies suggest a prevalence of 2-6% with palpation, 19-35% with ultrasound, 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 the most accurate and cost-effective method for evaluating and observing thyroid nodules. Current ultrasonography 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 or suspected thyroid nodule. The management of thyroid incidentalomas is a matter of controversy.