Abstract Prior to 1993, when ultrasound-guided core breast biopsy was first described by Parker and colleagues, surgery following image-guided needle localization was necessary to obtain a histological diagnosis of breast lesions. But there are many financial, practical, and clinical advantages of image-guided core biopsy over surgical excisional biopsy. There are also many advantages to ultrasound-guided biopsy over stereotactic- or MRI-guided biopsy, detailed in this chapter. Ultrasound is now usually the modality of choice by which to perform core biopsies if the lesion is visualized by multiple imaging modalities. This chapter, appearing in the section on interventions and surgical changes, reviews the key points of performing ultrasound-guided core biopsy. Topics discussed include protocols for both spring-loaded and vacuum-assisted devices; pre-procedure and post-procedure management, and imaging follow-up.