Secondary metabolites are low molecular weight compounds produced by plants in addition to primary metabolites. They include terpenes, phenolics, and nitrogen-containing compounds. Secondary metabolites provide benefits such as protecting against pests and attracting pollinators. They can be produced through plant cell and tissue cultures using bioreactors to provide medicines, flavors, food additives and other commercially important compounds in a more sustainable way than extracting from wild plants. Examples discussed include morphine, berberine, vinca alkaloids, ginseng, saffron, taxol and others.