AbstractBreast ultrasound (US) has developed into an essential imaging modality for evaluation and management of the patient with breast symptoms or mammographic abnormalities. US is usually an adjunct to mammography and the clinical examination but in the young patient presenting with symptoms sonography may be the initial or sole imaging procedure. A screening role has not been established, but there may be a subset of high‐risk patients for whom US will prove useful as a screening adjunct. Proper selection of equipment, careful attention to the technical aspects of scanning, and awareness of artifacts are necessary to avoid misinterpretation and to demonstrate subtle changes in breast architecture which indicate a malignancy. Thorough knowledge of the range of normal appearances of the breast and the alterations produced by breast disease are essential requisites for accurate evaluation and lesion characterization. Two of the most important clinical advances in breast US have been the development of criteria that allow improved benign/malignant differentiation of solid breast lesions and the use of US to guide interventional procedures. Other developments such as Doppler and contrast agents remain investigational.