A number of species of Dioscorea are cultivated largely for their large starchy tubers, commonly called yams, which are an important food crop in many parts of the world. Apart from several important edible species, a number of species accumulate quite high levels of saponins in their tubers which make them bitter and toxic, but these provide suitable sources of steroidal material for drug manufacture. Such species rich in steroidal sapogenins are of great pharmaceutical importance because of their relationship to compounds such as sex hormones, cortisone, diuretic steroids, vitamin D and cardiac glycosides. Diosgenin, one of the principal sapogenins in several Dioscorea species, is widely used as a precursor in the semi-synthesis of steroid hormones such as progesterone, corticosteroids and anabolic steroids. The cost of progesterone and other important steroids (till then synthesized) fell drastically in the 1940s with their successful semi-synthesis from diosgenin. There was and is thus a great demand for such natural products which will serve as starting materials for the partial synthesis of medicinally important steroids.