Abstract: A new carbazole alkaloid was isolated from the aqueous extract of the stems of Clausena lansium (Lour.) Skeels by various chromatographic methods, including HPD-100, PRP-512A, silica gel, and reverse phase C18. Its structure was determined by spectroscopic and chemical methods, including UV, IR, HR-ESI-MS, 1D/2DNMR and ECD. Compound 1, named as Claulamine F, showed no antimicrobial activity on Staphylococcus aureus, Escherichia coli or Pseudomonas aeruginosa. In addition, compound 1 exhibited no cytotoxicity on five kinds of cancer cells through MTT methods.