This study was undertaken to determine the absolute and relative value of blood vessel invasion (BVI) using both factor VIII-related antigen and elastica van Gieson staining, proliferating cell nuclear antigen (PCNA), p53, c-erbB-2, and conventional prognostic factors in predicting relapse-free survival (RFS) and overall survival (OS) rates associated with long-term survival in Japanese patients with node-negative breast cancer. Two hundred patients with histological node-negative breast cancer were studied. We investigated nine clinicopathological factors, including PCNA, p53, c-erbB-2 using permanent-section immunohistochemistry, clinical tumour size (T), histological grade (HG), mitotic index (MI), tumour necrosis (TN), lymphatic vessel invasion (LVI) and BVI, followed for a median of 10 years (range 1-20). Twenty-one patients (10.5%) had recurrence and 15 patients (7.5%) died of breast cancer. Univariate analysis showed that BVI, PCNA, T, HG, MI, p53, c-erbB-2 and LVI were significantly predictive of 20-year RFS or OS. Multivariate analysis showed that BVI (P = 0.0159, P = 0.0368), proliferating cell nuclear antigen (PCNA) (P = 0.0165, P = 0.0001), and T (P = 0.0190, P = 0.0399) were significantly independent prognostic factors for RFS or OS respectively. BVI, PCNA and T were independent prognostic indicators for RFS or OS in Japanese patients with node-negative breast cancer and are useful in selecting high-risk patients who may be eligible to receive strong adjuvant therapies.