Ethanol extract from Salvia miltiorrhiza (SME) was tested for breast cancer chemoprevention and metastasis by measuring the activites of cytochrome P45O 1A1, aromatase, ornithine decarboxylase (ODC), and matrix metalloproteinase (MMP)-9. SME significantly inhibited cytochrome P45O 1A1-mediated ethoxyresorufin O-deethylase (EROD) activity in a dose-dependent manner in a concentration range of 100${sim}$l,200 ${mu}g/ml$ (p<0.01). Microsomal aromatase (estrogen synthase) activity was suppressed 54.9%${sim}$77.5% by the SME at concentration of 600${sim}$l,200 ${mu}g/ml$. ODC activity induced by 12-O-tet-radecanoylphorbol-13-acetate (TPA) was significantly reduced by the SME 900 and 1,200 ${mu}g/ml$ (p<0.05) in MCF-7 breast cancer cells. In addition, SME (900 and 1,200 ${mu}g/ml$) markedly inhibited MMP-9 activity, a key role in cancer metastasis. Therefore, SME is worth further investigation with respect to breast cancer chemoprevention or therapy.