Abstract: Objective: To observe the morphologic characteristics of micro-lymphatic vessels marked by using a novel monoclonal antibody, D2-40, against lymph epithelial cells, and to analyze the relationship between lymph node spread and the micro-lymphatic vessel density (MLVD) at the intratumoral and peripheral regions in epithelial ovarian tumors. Methods: Tissues were collected from 85patients with epithelial ovarian carcinomas (EOC) and 20patients with benign ovarian tu -mors and embedded in paraffin after surgery, from Jan1, 1998to April 30, 2003, in the Cancer Center at Sun Yat-sen Uni -versity. The expression of MLVD by SP immunostaining using D 2-40monoclonal antibodies was examined, and the posi-tive micro-lymphatic vessels marked by D 2-40were counted. All statistical calculations were carried out using the statistical software SPSS 13.0. The Student t-test and Chi-square test were used to analyze the data. Results: In 85EOC cases, D2-40only marked the lymphatic vessels which had thin walls and irregular lumens and shapes. The positive rate of D 2-40 staining was 75.2% (64/85) in EOC. MLVD at intratumoral and peripheral regions was 7.50(7.00± 1.72) and 28.19(27.11± 2.44)/ 100 field, respectively. The MLVD in peripheral regions was significantly higher in patients with lymph node metasta -sis than that in patients without metastasis 32.00(31.01± 1.23) vs. 21.10(20.44± 1.41)/ 100 field, P=0.001 , but there was no difference in intra-tumoral regions 5.50(5.31± 0.75) vs. 5.967 (5.65± 1.02) / 100 field, P=0.293 . Conclusion:Micro-lym-phatic vessels, which were marked by the new monoclonal antibody D2-40, mainly lie in peripheral regions. The retroperito -neal lymphatic metastasis of EOC may be associated with the formation of micro-lymphatic vessels. It may be necessary to inhibit the formation of lymphatic vessels while inhibiting tumor angiogenesis in the treatment of cancer.