Abstract The benefits of preoperative diagnosis in breast cancer are now well established and include appropriate planning of operating lists and patient involvement in therapeutic options. The use of intraoperative frozen section is thus considered by many now to be unacceptable and preoperative diagnostic methods have replaced its use. These include fine needle aspiration cytology and needle core biopsy. We describe in this manuscript the basic principles of needle core biopsy use and recommendations for reporting of these samples into five diagnostic categories as recommended by the National Health Service Breast Screening Programme in the UK. In addition, we address problem areas and potential pitfalls in needle core biopsy diagnosis and describe some of the more common difficulties that the pathologist may encounter. Finally, we briefly describe alternative uses for core biopsy including the potential evaluation of prognostic factors such as histological grade and predictive factors such as oestrogen receptor.