The argyrophilic nucleolar organizer regions (Ag-NORs) was measured in the tissue sample aspirated with fine needle for 17 cases of breast benign lesion and 46 cases of breast cancer, by analysis of their micro-image with light microscope and computed. The results indicated that the amount of Ag-NORs in the nuclei of breast cancer was increased while the percentage of average areas occupied by Ag-NORs was decreased. It was significant statistically in comparing with benign lesion (P < 0.05). In addition, the amount of Ag-NORs in the nuclei of breast cancer with and that without metastasis was not different markedly (P > 0.05). However the percentage of average areas occupied by Ag-NORs was different statistically (P < 0.05). The conclusion of Ag-NORs is of benefit to distinguish from benign and malignant tumours of breast as well as significant for evaluating the prognosis for breast cancer.