We examined the anti-invasive activity of ginsenosides Rhl, Rha on the highly metastatic HT1080 human fibrosarcoma cell line. In vitro invasion assay showed ginsenoside Rhr reduced tumor cell invasion through a reconstituted basement membrane in a transwell chamber more than ginsenoside Rh1. Significant down-regulation of matrix metalloproteinase-9 (MMP-9) by ginsenosides Rh, and Rh2 was detected by Northern blot analysis. However, the expression of MMP-2 was not affected by Rh, and Rhr. The expression of tissue inhibitor of metalloproteinase-2 (TIMP-2) was increased by Rhl after 0.5, 1 or 3 day-treatment but reduced after 6 day-treatment. However, the expression of TIMP-2 was not changed by treatment with Rh2. Plasminogen activator inhibitor (PAI) and urokinase-type plasmlnogen activator (uPA) were not changed by treatment with Rh1 and Rh2 for 3 and 6 days. Quantitative gelatin-based zymography confirmed a markedly reduced expression of MMP-9 but MMP-2 after treatments with ginsenosides Rhl and Rha. These results suggest that down-regulation of MMP-9 contributes to the anti-invasive activity of ginsenosides Rhl and Rhr in the HT1080 cells.