From the fruits of Arctium lappa L. (Japanease name"goboshi, ""akujitsu, "or "dairikishi"), two new sesquilignan derivatives, AL-D and AL-F, were isolated along with arctin, arctigenin, and matairesinol. From spectroscopic and chemical investigations, the structure of AL-D was elucidated as 2-[2-(3-methoxy-4-hydroxy) phenyl-3-hydroxymethyl-7-methoxy-2,3-dihydrobenzofuran-5-yl] methyl-3-(3-methoxy-4-hydroxy)-benzyl-buthyrolactone [I] or 2-(3-methoxy-4-hydroxy) benzyl-3-[2-(3-methoxy-4-hydroxy)-phenyl-3-hydroxymethyl-7-methoxy-2,3-dihydrobenzofuran-5-yl] methyl-buthyrolactone [II]. AL-F was found to be a stereoisomer of AL-D.