Curcumin is a natural component of the rhizome of turmeric (Curcuma longa) and one of the most powerful chemopreventive and anticancer agents. Its biological effects range from antioxidant, anti-inflammatory to inhibition of angiogenesis and is also shown to possess specific antitumoral activity. The molecular mechanism of its varied cellular effects has been studied in some details and it has been shown to have multiple targets and interacting macromolecules within the cell. Curcumin has been shown to possess anti-angiogenic properties and the angioinhibitory effects of curcumin manifest due to down regulation of proangiogenic genes such as VEGF and angiopoitin and a decrease in migration and invasion of endothelial cells. One of the important factors implicated in chemoresistance and induced chemosensitivity is NFkB and curcumin has been shown to down regulate NFkB and inhibit IKB kinase thereby suppressing proliferation and inducing apoptosis. Cell lines that are resistant to certain apoptotic inducers and radiation become susceptible to apoptosis when treated in conjunction with curcumin. Besides this it can also act as a chemopreventive agent in cancers of colon, stomach and skin by suppressing colonic aberrant crypt foci formation and DNA adduct formation. This review focuses on the various aspects of curcumin as a potential drug for cancer treatment and its implications in a variety of biological and cellular processes vis-à-vis its mechanism of action (PMID: 16712454). Turmeric (Zingiberaceae family) rhizomes, has been widely used for centuries in indigenous medicine for the treatment of a variety of inflammatory conditions and other diseases. Its medicinal properties have been attributed mainly to the curcuminoids and the main component present in the rhizome is curcumin. Curcumin has been shown to possess wide range of pharmacological activities including anti-inflammatory, anti-cancer, anti-oxidant, wound healing and anti-microbial effects. Recently, curcumin treatment has been shown to correct defects associated with cystic fibrosis in homozygous DeltaF508 cystic fibrosis transmembrane conductance regulator (CFTR) knock out mice. In vivo and in vitro studies have demonstrated curcumin's ability to inhibit carcinogenesis at three stages: tumor promotion, angiogenesis and tumor growth. Curcumin suppresses mitogen-induced proliferation of blood mononuclear cells, inhibits neutrophil activation and mixed lymphocyte reaction and also inhibits both serum-induced and platelet derived growth factor (PDGF)-dependent mitogenesis of smooth muscle cells. It has also been reported to be a partial inhibitor of protein kinase. The other salient feature of turmeric/curcumin is that despite being consumed daily for centuries in Asian countries, it has not been shown to cause any toxicity (PMID: 16413584).