Two new geranyl bearing polyisoprenylated benzoylphloroglucinol derivatives, hypersampsone G (1) and hypersampsone H (2) were isolated from the fruit of Hypericum sampsonii. Their structures were determined on the basis of spectroscopic data and the structure of 1 was confirmed by X-ray crystallographic analysis. Antitumor activities on A549 human cancer cells of the two compounds were tested.