Fine-needle aspiration cytology has been an established method in complementary breast diagnosis since the publications of Martin and Ellis in 1930. Core biopsy, however, has only recently found broader application with the introduction of automatic spring-acting puncture devices. Excellent results have been reported recently in the literature (Parker et al. 1994). The goal of both of the aforementioned interventional methods is to improve the specificity of breast diagnosis and thereby avoid unnecessary open breast biopsies with benign histology. The establishment of the diagnosis of invasive or noninvasive breast cancer preoperatively is of ever increasing importance for the individual tailoring of the operative treatment of breast carcinoma.