Since its introduction in the 1960s, ultrasound (US) has never been more important in breast disease management as it is today. Its historical role as an adjunct modality to mammography in differentiating cystic from solid lesions has been widely expanded. US-guided sampling procedures represent widely accepted modalities in lesion evaluation. Preoperative localization under US guidance is one of the methods of choice for nonpalpable solid lesions. Screening breast US is currently being investigated and might prove useful for high-risk women and women with dense breasts. Continuous technologic advances, such as high-frequency transducers, new Doppler-based techniques, microbubble contrast agents, harmonic and compound imaging, three-dimensional US, elasticity imaging, US detection of microcalcifications, perfusion US imaging, and computer-aided diagnosis all carry promise of further increases in US utility in the diagnosis and detection of breast disease.