Abstract: This article reports on our experience with core needle biopsy (CNB) of the breast and presents a review of the literature. We have performed CNB on 304 women with abnormalities classified on imaging as highly suggestive of malignancy (52 cases), suspicious (245 cases) or probably benign (7 cases). The CNB procedure was performed using either stereotactic mammographic guidance (251 cases) or ultrasound guidance (53 cases) with a 14-gauge needle. At least five specimens were obtained for each abnormality. The sensitivity of core biopsy was 98% and the specificity was 99%. There were three false negatives and one false positive. An excisional biopsy was recommended in 17 cases in which the CNB diagnosis was not definitive, including 12 with atypical ductal hyperplasia (ADH), 4 with discordance between imaging and histologic results, and 1 with inconclusive histology. Our results are consistent with other reports in the literature using 14-gauge core needle biopsy. In our practice, core biopsy has proven to be an effective method for the evaluation of imaging findings that are suspicious or highly suggestive of malignancy.