Aucklandia lappa Decne. is indigenous in India, Pakistan and China. It is widely used in traditional ancient medicines of China, Ayurveda and Tibet. Its active constituents are terpenes but also anthraquinones, alkaloids and flavonoids which possess antifungal, antimicrobial, anthelmintic, antitumor, antiulcer, immunostimulant, antiinflammatory and antihepatotoxic properties [1]. Aim of this study was to optimize the extraction method of the roots of A. lappa and to evaluate the minimum content of costunolide and of the sum of costunolide and dehydrocostus lactone. As a starting point the Monograph of the Chinese Pharmacopoeia was used [2]. 14 different extraction methods were evaluated. Maceration time, shaking time, the type of sonication and the duration were investigated. The best extraction method was 1 hour of shaking plus 30 minutes of sonication bath, using 100% methanol. 1H-NMR analysis was performed directly on the powered herbal drug using deuterated DMSO to extract the constituents. Characteristic signals of both sesquiterpenes were not present in the extracted herbal drug. The optimized method is able to extract from 82.2% to 97% of sesquiterpens lactones saving 23 hours. The minimum content of costunolide and dehydrocostus lactone in 7 different samples was calculated. Five samples contained more than 1.8% of the sum of constituents, according to Chinese Pharmacopoeia limits. A high instability of sesquiterpenes was found after powdering the herbal drug with a loss of about 20% of active compounds after 15 – 20 days. It is strongly suggested to use fresh herbal drug powder to avoid errors in the quantification of constituents.