PURPOSE: Multiple clinical, biological, and pathologic factors correlate with the outcomes in patients with invasive breast cancer. The utility of a peritumoral vascular invasion (PVI) as an additional prognostic indicator has been poorly defined. The aim of this study was to determine if the presence or absence of PVI can be used to help assess the survival and recurrence. METHODS: An invasion of the vascular space (lymphatic and/or blood vessel) by a tumor, as assessed on routine hematoxylin and eosin sections, was investigated in a 146 women with primary operable invasive breast carcinoma. The presence of PVI was compared with the established prognostic factors such as age, tumor size, axillary lymph node involvement, histological grade, hormonal receptor status, and expression of c-erb B2, Ki-67 and p53. Survival analysis was performed using Kaplan-Meier method and log-rank test. RESULTS: PVI was found in 35.6% of cases and was significantly associated with an increasing tumor size (P=0.033) and metastatic axillary lymph nodes (P=0.012). The 5 year disease free survival (DFS) and overall survival (OS) were significantly lower in the patients with PVI than without PVI (P=0.0431 and 0.0445, respectively). In multivariate analysis, the axillary lymph node status (P=0.001), the tumor size (P=0.044) and PVI (P=0.050) were significant independent prognostic factors for the DFS. In the node- negative breast cancer group and in the node-positive breast cancer group, the 5 year DFS and OS were lower in the patients with PVI than in those without, but this did not show significant difference. CONCLUSION: Cox multivariate analysis showed that PVI is a strong prognostic factor for patients with operable invasive breast cancer and an independent prognostic factor for a recurrence. A histological assessment of PVI can provide prognostic information on primary operable invasive breast carcinoma and might be helpful in making a clinical decision.