Breast needle core biopsy (NCB) is now a commonplace diagnostic procedure in breast cancer screening, providing accurate diagnoses of both benign and malignant lesions. However, NCB may result in the borderline diagnoses of lesion of uncertain malignant potential (B3) or suspicious of malignancy (B4). The aim was to study a large series of B3 cases from population-based screening subjects in order to evaluate positive predictive values (PPVs) for malignancy.