In the preliminary antitumor screening tests of Crude Drugs and collected plants, the methanol ic extract of Forsythia Fruits in Korean marcket showed signif icant cytotoxic activity against Chinese hamster V-79 cells, but that in Japanese market did not. The former was identifid as Forsythia viridissima Lindley and latter as F.suspensa Vahl on the basis of the morphological observation. When an aqueous solution of the extract prepared from the fruits of F. viridissima (Oleaceae) was partitioned successively with n-hexane, methylene chloride, n-butanol, the cytoyoxic activitywas concetrated in the methylene chloride extract. Fractionation of the extract was made with the guidance of bioassay against V-79 cells to give cytotoxic lignans, matariresiol (1) and arctigenin (2). Their ICso values of compounds 1 and 2 were respectively 7.8μg/ml 1 and 1.65μg/ml. Also, their structures were confirmed by comparison of physical and spectral data in the literature.