Abstract: Objective：To investigate the expression of Prox1 in human breast carcinoma and its relationship with clinical pathologic characters. Methods ：The expression of Prox1 was detected by SP immunohistochemistry in 11 specimens of hyperplasia of mammary glands，80 specimens of breast cancer (30 with lymphatic metastasis). Results ：The expression of Prox1 in 11 specimens of hyperplasia of mammary glands was completely negative，but were 62.5%(50/80)of the carcinoma nests cells and 65.0%(52/80)of lymphatic endothelial cells in breast cancer specimens.The percentage of cells positive for Prox1 in breast cancer patients with metastasis (76.7%, 23/30) was higher than those without (54.0%, 27/50), as well as in lymphatic endothelial cells with metastasis (83.3%, 25/30) than those without (54.0%, 27/50).The differences of two groups have statistical significance (P<0.05).The expression of Prox1 in the lymphatic endothelial cells of lymphatic metastasis specimens was correlated with the numbers of invaded lymph nodes (P<0.05).However, no significant correlation was found between Prox1 expression level and the following clinical parameters: age, ER status, PR status, HER2 status(P>0.05).Positive correlation(r=0.452, P<0.001)of the Prox1 expression was found between carcinoma cells and lymphatic endothelial cells, and Prox1 expression in carcinoma cells and lymphatic endothelial cells were both positively correlated with TNM stage(r=0.589, P<0.001). Conclusion ：The high expression of Prox1 may be correlated with the process of breast cancer progression and metastasis.