Lymphovascular invasion (LVI) by tumor cells is histologically evident in approximately 15% of invasive mammary duct carcinomas and is present in approximately 10% of cases with pathologically negative lymph nodes. LVI is indicative of unfavorable prognosis in the breast cancer-as manifested by increased local failure and reduced overall survival. It is for this reason that LVI is routinely included in the evaluation and reporting of all breast cancers. There are a variety of interpretative difficulties in the histopathologic assessment of LVI, and the clinical implications of any misinterpretation can be profound. This brief review seeks to highlight the difficulties in the evaluation of LVI in breast cancer.