Abstract: OBJECTIVE To investigate the anti-metastatic effect of Alisol B on 4T1 breast cancer cells and explore its possible mechanisms. METHODS 4T1 breast cancer cells were treated with Alisol B for 24 h. Cell viability was evaluated by MTT assay. Migration ability was evaluated by wound healing assay. Invasion ability was investigated by transwell invasion assay. The expressions of matrix metalloproteinases (MMP-2 and MMP-9) were detected by Western blot analysis. RESULTS Alisol B showed inhibitory effect on cell growth in 4T1 cells. Wound healing assay demonstrated that Alisol B inhibited the migration of 4T1 cells after the treatment for 24 h. The migration rate was (52.66±8.48)% (P<0.01). Transwell invasion assay proved that Alisol B effectively suppressed the invasion of 4T1 cells．The invasion rate was (47.06±9.32)% (P<0.01). Western blot results demonstrated that the expression of MMP-2 and MMP-9 were significantly down-regulated with the treatment of Alisol B. CONCLUSION Alisol B can suppress the metastasis of 4T1 breast cancer cells in vitro， which could be through down-regulation the expression of matrix metalloproteinases.