AbstractUrethane polymers comprise one of the most rapidly expanding areas of the organic chemical industry. Polyurethane production, estimated at about 100 million lb in 1960, is expected to rise to 500 million lb in 1965 and to have an ultimate potential in excess of a billion lb. The polymers are used in foams (flexible, semi‐rigid and rigid), plastics, fibers, solid elastomers, surface coatings and adhesives. Fat‐ and oil‐derived products have potential utility in all these applications. Fat‐derived reactants include natural glycerides (e.g., castor oil), and other esters derived from reaction of fatty acids with polyols such as glycerol, pentaerythritol, sorbitol, sucrose, alkanol amines, etc., polymerized fatty acids, alkylene oxide derivatives of fatty acids and tall oil. The reactions of primary importance in the production of polyurethanes from isocyanates, including the urethane reaction, urea reaction, allophanate and biuret formation are discussed. A generalized treatment of the chemical technology involved in the preparation of representative polyurethane products is presented and the major areas in which fat and oil products are finding application in polyurethanes are noted.