Anthocyanins have been shown to exhibit anti-carcinogenic activity against multiple cancer cell types in vitro and tumor types in vivo. Potential cancer chemopreventive activities of anthocyanins revealed from in vitro studies include radical scavenging activity, stimulation of phase II detoxifying enzymes, reduced cell proliferation, inflammation, angiogenesis and invasiveness, and induction of apoptosis and differentiation. The anthocyanins modulate the expression and activation of multiple genes associated with these cellular functions including genes involved in the PI3K/Akt, ERK, JNK, and MAPK pathways ( Fig. 2). In vivo studies have shown that dietary anthocyanins inhibit cancers of the gastrointestinal (G.I.) tract and topically applied anthocyanins inhibit skin cancer. Pharmacokinetic data indicate that the absorption of anthocyanins into the bloodstream of rodents and humans is minimal, suggesting that they may have little efficacy in tissues other than the G.I. tract and skin, where they can be absorbed locally. Measuring tissue-bound anthocyanins should be done to predict the chemopreventive effects of anthocyanins in different organ sites. The role of gut bacteria in the metabolism and uptake of anthocyanins should also be investigated. Finally, studies should be undertaken to determine if the anti-cancer effects of anthocyanins are due to the parent compounds and/or to their metabolites.