Fourteen prenylated xanthone derivatives were isolated from gamboge, the dry latex of Garcinia hanburyi, and their structures were elucidated by a detailed spectroscopic analysis. Five of them, isogambogenic acid (1), desoxymorellinin (2), 10-methoxygambogenic acid (3), 10-methoxygambogic acid (4) and 10-ethoxy gambogic acid (5), are new compounds. All of them showed potent cytotoxicity against HL-60, SMMC-7721 and BGC-83 cells.