Stereotactic core biopsy is becoming increasingly popular as a technique which provides a histologic diagnosis for mammographic abnormalities while avoiding the trauma, deformity, and much of the cost associated with surgical biopsy. This review evaluates the published literature on the diagnostic accuracy of core biopsy for ductal carcinoma in situ and invasive breast cancer and the ability of core biopsy to characterize malignant lesions sufficiently to allow treatment planning. Issues of cost effectiveness are examined in the context of the degree of suspicion of the mammographic abnormality being sampled by core technique as well as subsequent breast cancer therapy.