The conversion of animal byproducts into useful edible and nonedible products has existed for a very long time. The rendering process recycles animal and poultry byproducts such as fat, bones, hide, offal, feathers, hoofs, horns, hair, and blood. In fact, byproducts represent from 37% to 50% of the live weight of the various meat animals and as much as 57% of the live weight of many fish species. The average annual production of red meat and poultry is 250 million tons, so the potential availability of raw material to produce byproducts could be 92.5–125 million tons per year. The major rendered animal byproducts, including fish, fall into two categories: proteins and fats. These products compete on the world commodity market, so their prices tend to rise and fall with supply and demand. Prices and availability also are affected by other situations, for example, the mad cow disease problem for rendered animal byproducts and the weather phenomenon, El Niño, for fish byproducts. The protein products are primarily used in the feeds of various livestock, including poultry, pigs, ruminants, pets, and fish. The fat and oil products find use in a variety of markets including the feeding industry, the technical or industrial market, and human foods. Fish oil has a unique set of fatty acids called omega 3's, which obtained US FDA GRAS (generally recognized as safe) acceptance in 1995 and in 2004 received approval to make a qualified health claim related to cardiovascular disease. Animal fats are beginning to find new technical uses in the oleoochemical area and use in bio-fuels (as is) and in bio-diesel products (conversion to methyl esters). As a result of ever changing environmental, social, health, and sustainability issues, the future of the industry will depend on the ability of the participants to adapt to these changes.