The use of a good, adequate, and industrially usable medium is as important as the deployment of a suitable microorganism in industrial microbiology. Unless the medium is adequate, no matter how innately productive the organism is, it will not be possible to harness the organism’s full industrial potential. Liquid media are generally employed in the industry because they require less space, are more amenable to engineering processes, and eliminate the cost of agar. All microbiological media should satisfy carbon, nitrogen, minerals, growth factors, and water needs of the organism. Data on composition of bacteria, yeast and molds are used as reference in calculations of nutrient requirements. Under laboratory conditions, it is possible to meet the organism’s requirement by the use of purified chemicals since microbial growth is generally limited to a few liters. However, on an industrial scale, the volume of the fermentation could be in the order of thousands of liters. Therefore, pure chemicals are not usually used because of their high expense, unless the cost of the finished material justifies their use. This chapter presents the criteria for raw materials in industrial media, growth factors, water, carbohydrate sources, protein sources, starch, cellulose, hemicelluloses and waste materials.