The various techniques of plant-tissue culture have made possible medicinal plant improvement through genetic engineering, selection of higher yielding strains, generation of novel metabolites in culture, isolation of biosynthetic enzymes, and production of secondary metabolites of plant cells in much higher yields than in intact plants. Plant-tissue culture could thus be a significant source of phytochemicals used as pharmaceuticals, food additives, fragrance chemicals, and pesticides. Cell-suspension cultures have been used to generate a large number of alkaloids, steroids, volatile oils, saponins, cardiac glycosides, anti-cancer agents, insecticides, and volatile terpene constituents. Novel plant products not made by whole plants have been formed in cultured cells from precursors added to the media. Large-scale production of plant products similar to microbial fermentative production has generated scores of compounds in culture such as berberine, ajmalicine, fucin, colchicine, anthraquinones, quinine, jasmine, diosgenin, morphine, codeine, camptothecin, nicotine, glycyrrhizin, and stevioside among others.