AIM To study antiinvasive and antimetastatic activities of fagopyrun cymosum meissn on B16BL6 melanoma cells (highly metastatic cell line) and inhibitory effect on type Ⅳ collagenase production of HT1080 cells. METHODS Reconstituted basement membrane invasion assay was utilized to evaluate the invasive activity of cancer cells. Tyep Ⅳ collagenase production was assessed by PAGE substrate zymography. WST assay was used to examine the cytotoxicity of fagopyrun cymosum meissn. RESULTS The extract of fagopyrun cymosum meissn significantly inhibited membrane invasion of B16BL6 bearing C57/BL6 cell at a concentration of 100 mg·L-1 and effectively suppressed the spontaneous lung metastasis on B16BL6 bearing C57/BL6 mice at the dosage of 200 mg·kg-1. Extract of fagopyrun cymosum inhibited the production of type Ⅳ collagenases of human fibrosarcoma cells line HT1080 but it has no effect on the activity of this enzyme. CONCLUSION Extract of fagopyrun cymosum meissn has the notable inhibitory effects on tumor invasion and metastasis. Type Ⅳ collagenase inhibition may correlate with the antiinvasive and antimetastatic activities of Fagopyrun cymosum.