Turmeric, a rhizomatous herb, contains curcuminoids and essential oil, which are two major classes of secondary metabolites. These compounds are largely responsible for the pharmacological effects of turmeric. The three major curcuminoids are curcumin, demethoxycurcumin (DMC), and bisdemethoxycurcumin (BDMC). Curcumin is the most abundant curcuminoid present in turmeric rhizomes followed by demethoxycurcumin and bisdemethoxycurcumin. The curcuminoids' mixture, which we get on a commercial scale, contains 78% curcumin, 18% DMC and 4% BDMC. A brief account of the chemical compositions and natural analogues of turmeric has been discussed in this chapter. The composition of turmeric and natural analogues, their antioxidant activities and pharmacological activities are also presented in this chapter.