Carotenoid, a natural functional pigment, is known to have anti-carcinogenic activity. To verify the anti-cancer effects of rhodoxanthin which is a kind of carotenoids, we investigated the effects of rhodoxanthin from Potamogeton crispus L. on the proliferation rate, cell cycle distribution, apoptosis and the change in mitochondrial membrane potential in Hela cell line. The effects of rhodoxanthin were also tested on the concentration of Ca(2+) in cells. Rhodoxanthin inhibited cell proliferation in Hela cells in a dose and time-dependent manner. Rhodoxanthin induced an accumulation of cells in the S phase of the cell cycle, reduced the mitochondria transmembrane potential and increased the concentration of intracellular Ca(2+). In summary, our results suggested that rhodoxanthin-induced apoptosis in Hela cells occurred via these pathways.