Plants contain an enormous diversity of biologically active chemicals and secondary metabolites which are called phytochemicals. Till date more than 4000 compounds have been discovered and isolated. The most important action of phytochemical is that they function as antioxidants that react with free oxygen and free radicals in our bodies. Free radicals can damage the cells in our body and are involved in the pathology of many diseases like Cancer, Diabetes, Inflammation, Cardiovascular problems etc. Phytochemicals such as flavonoids alkaloids, tannins, glycosides, polyphenols, phyto-oestrogens, terpenoids, carotenoids, sterols etc. There is increasing evidence that phytochemicals are potentially beneficial for human health. Hence there is more scope in identifying phytochemicals constituents for curing various human diseases.