BACKGROUND: Lymphatic vessel invasion (LVI) has been conventionally assessed on hematoxylin-eosin (HE) stained sections, but this assessment tends to be subjective. The aim of this study is to investigate the significance of LVI in invasive breast cancers, primarily using immunohistochemical lymphatic endothelial markers. METHODS: We studied 69 invasive breast carcinoma cases. Using D2-40 and podoplanin, we investigated the distribution of lymphatic vessels around the tumor and LVI, and they were compared with the HE sections. The correlation between LVI, lymph node metastasis and disease free survival (DFS) was also investigated. RESULTS: Lymphatic vessels were most frequently seen outside the tumor (86%), whereas lymphatic vessels were not seen in the central zone of the tumor. LVI was found in 22 cases, of which nineteen was seen in the peripheral zone (87%). For both HE and lymphatic markers, the rates of mild LVI tended to be high. The concordance rate between D2-40 and podoplanin was 94.2% (65/69). LVI assessed on HE sections was corresponded to 54/69 cases (78.2%) using either D2-40 or podoplanin. There were 25 axillary lymph node positive cases. Lymph node metastasis significantly correlated with LVI assessed by HE section, but did not correlate with LVI assessed by the lymphatic markers. The tumor recurred in 19 cases during the mean follow-up period of 47.5 months. Disease free survival was significantly better for LVI negative cases on HE analysis, and LVI negative or mildly positive by any staining procedure. CONCLUSION: The lymphatic endothelium markers, D2-40 and podoplanin, are very useful for detecting LVI, but careful examination by routine HE sections may be enough for routine practice. Moderate or marked degree of LVI may be of value to predict survival.