Objective: To investigate the relationship between matrix metalloproteinases-9 (MMP-9) and sialyl Lewis X (CD15s) antigen in invasion and metastasis of gastric carcinoma. Methods: Expression of CD105, MMP-9 and CD15s in 47 cases of gastric carcinoma undergone radical surgery were evaluated by SP immunohistochemical staining using the respective monoclonal antibody. The microvessel density (MVD) marked with CD105 was detected. Correlation between MVD and MMP-9, CD15s was also statistically analyzed. Results: The MVD in both MMP-9 and CD15s positive expression group was higher significantly than that in MMP-9 or CD15s positive expression alone group, and it was also significantly higher than that in both MMP-9 and CD15s negative expression group. Conclusion: MMP-9 is a marker of invasion and CD15s is a marker of metastasis in gastric carcinoma. Combining detection of MMP-9 and CD15s has certain clinical significance for diagnosis,treatment and assessing the prognosis for gastric caner.