Selaginellae Herba has been used as folk medicine for antineoplastics, coagulants, antidotes and invigorants. To find an in vitro screening method for liver protective effect of Selaginellae Herba in benzo(a)pyrene intoxicated injury were examined in primary cultured rat hepatocytes. Using MTT assay, herba concentration showed dose dependently viability. The lowest concentration of benzo(a)pyrene giving cytotoxicity revealed around 50gM. The hepatoprotective effect of Selaginellae Herba in both water and chloroform extracts was also increased dose dependently.