A new lignan glycoside, named eleutheroside E 2 (1), has been isolated from the roots of Eleutherococcus senticosus (known as ªSiberian ginsengº), along with isomaltol 3-O a-glucopyranoside (2), eleutherosides B, E and E 1, and thymidine. The structure of 1 was established by spectral interpretations as episyringaresinol 4¢¢-O b-D-glucopyranoside. Compound 2 is described here for the first time as a naturally occurring compound. The chemistry and pharmacology of the Far Eastern plant, Eleutherococcus senticosus (Rupr. and Maxim.) Maxim., which is commonly known as Siberian ginseng and used as a tonic and adaptogen, have been studied extensively (1). In recent years this plant has again gained popularity in the United States. A considerable number of herbal products containing Siberian ginseng root extract are available on the market. Two major glycosides present in this plant, eleutheroside B (= syringin) and eleuthereoside E (= syringaresinol 4¢,4¢¢-di-O-b-Dglycopyranoside), are usually served as marker compounds for the fingerprinting of these commercial products (2). During the isolation of the marker compounds from this plant, a minor new lignan glycoside has been obtained, along with isomaltol 3-O a-D-glucopyranoside (2) (3), eleutherosides B (4), E (5) and E 1 (= syringaresinol 4¢-O b-D-glycopyranoside) (5), and thymidine (6). Compound 2 was previously reported as a chemically degraded compound of maltose when heated with secondary amino acids (3). It is described here for the first time as a naturally occurring compound.