(+)-Guaiacin, a trans(2,3)-trans(3,4) phenyltetralin lignan, has been isolated for the first time from the stem bark of Machilus edulis King (Lauraceae) together with dihydroguaiaretic acid. Contrary to earlier observations, (+)-guaiacin has been converted by two different routes to (+)-galbulin, a new optical antipode of (-)-galbulin. Physical properties including NMR and MS data as well as chemical degradation reactions are reported for the first time for these lignans. © 1972.