Catechin compounds, abundant mainly in green tea, have chemo-preventive effects against carcinogenesis. The green tea used in this experiment was cultivated at Bosung (Chonnam, Korea) and purchased from a domestic market. The extract at 50°C water from the powder of Korean green tea was partitioned with chloroform and ethyl acetate. The resulting solution was further purified on a preparative column (4.6×250 mm, 15μm). Finally separation was achieved on a μ-Bondapak C18(3.9×300 mm, 10 μm) column.