Cholesterol is an extremely important biological molecule that has role in membrane structure as well as precursor for the synthesis of steroid hormones, bile acids and vitamin D. Cholesterol is converted to bile acid and excreted, cholesterol is mainly excreted in the form of bile salts in stools. Methods for estimation of total serum cholesterol are colorimetric method—Zak’s method and enzymatic method—cholesterol oxidase-peroxidase method. Cholesterol esterase is used to free the cholesterol from cholesterol ester. Free cholesterol is oxidized by cholesterol oxidase and produces hydrogen peroxide, which gives pink color on reacting with phenol and 4-aminoantipyrine.