Pretreatment of the methanolic extract(250-500mg/kg, p.o., two weeks) of Lysimachiae Herba prevented the elevation of ALT and AST activities in galactosamine(GalN, 400 mg/kg, i.p.) intoxicated rats. Its five fractions, especially the ethyl acetate fraction, also showed significant preventing actions on damaged liver metabolizing enzyme functions by GalN intoxication.