A new guaianolide, notoserolide E, along with nine known compounds was isolated from the Chinese endemic plant of Notoseris henryi ( Dunn ) Shih and its structure was elucidated by means of spectroscopic evidence. A new guaianolide, notoserolide E, along with nine known compounds was isolated from the Chinese endemic plant of Notoseris henryi (Dunn) Shih and its structure was elucidated by means of spectroscopic evidence.