AbstractThyroid nodules are a common finding in the general population. Ultrasonography is the most sensitive imaging tool for diagnosing thyroid nodules. However, sonographic differentiation of hormonally active versus inactive nodules, and in particular benign versus malignant nodules, remains unreliable. In this context, thyroid scintigraphy has its clinical significance predominantly in diagnosing hormonal activity of thyroid nodules. However, most nodules are benign and a significant number of patients undergo surgery for diagnostic rather than for therapeutic reasons. Efforts of the past years aimed to improve sonographic risk stratification, to predict malignancy of thyroid nodules through standardized diagnostic assessment of validated risk factors, in order to select patients who require further diagnostic workup. In the last years, several imaging and reporting systems, giving standardized categories with rates of malignancy, were evaluated as a basis for further clinical management. Recent technological developments, such as elastography, also show promising data and might be implemented into clinical practice. Ultrasound-guided fine needle aspiration is the key element in the diagnosis of sonographically suspicious thyroid nodules and significantly contributes to the diagnosis of malignancy versus benignity.