Pursuant to a legislative requirement, GAO reviewed the Food and Drug Administration's (FDA) new rule on animal feed additives. GAO noted that: (1) the rule would prevent the establishment and amplification of bovine spongiform encephalopathy in the United States through feed and, thereby, minimize the risk of transmission to animals and humans; (2) this rule amends FDA regulations to provide that animal protein derived from mammalian tissues for use in ruminant feed is a food additive subject to certain provisions in the Food, Drug, and Cosmetic Act; and (3) FDA complied with applicable requirements in promulgating the rule.