Lycopus lucid us Turcz is well known as traditional Chinese medicine, and it has been shown to exhibit antiinflammatory, -allergic and -oxidative effect. However, its anti-cancer properties have not been examined yet. In this study, we investigated the effect of the methanol extract of Lycopus lucid us Turcz on anti-cancer effect in MCF-7 human breast cancer cells. Treatment of Lycopus lucidus Turcz extract induced apoptosis and inhibition of cell proliferation in dose- and time-dependent manner. Apoptosis in the MCF-7 cells was characterized with the changes in nuclear morphology; decrease of Bcl-2 and caspase-7 expression; and increase of cleaved poly ADP-ribose polymerase(PARP). Furthermore, treatment of Lycopus lucidus Turcz extract caused the down-regulation of cell cycle-related protein including, cdk4, cyclin D1 and E2F-1. These results suggest that Lycopus lucidus Turcz might have the therapeutic value against human breast cancer cells.