Genetically modified (GM) Bt corn, through the pest protection that it confers, has lower levels of mycotoxins: toxic and carcinogenic chemicals produced as secondary metabolites of fungi that colonize crops. In some cases, the reduction of mycotoxins afforded by Bt corn is significant enough to have an economic impact, both in terms of domestic markets and international trade. In less developed countries where certain mycotoxins are significant contaminants of food, Bt corn adoption, by virtue of its mycotoxin reduction, may even improve human and animal health. This paper describes an integrated assessment model that analyzes the economic and health impacts of two mycotoxins in corn: fumonisin and aflatoxin. It was found that excessively strict standards of these two mycotoxins could result in global trade losses in the hundreds of millions $US annually, with the US, China, and Argentina suffering the greatest losses. The paper then discusses the evidence for Bt corn’s lower levels of contamination of fumonisin and aflatoxin, and estimates economic impacts in the United States. A total benefit of Bt corn’s reduction of fumonisin and aflatoxin in the US was estimated at $US annually, with the US, China, and Argentina suffering the greatest losses. The paper then discusses the evidence for Bt corn’s lower levels of contamination of fumonisin and aflatoxin, and estimates economic impacts in the United States. A total benefit of Bt corn’s reduction of fumonisin and aflatoxin in the US was estimated at 23 million annually. Finally, the paper examines the potential policy impacts of Bt corn’s mycotoxin reduction, on nations that are making a decision on whether to allow commercialization of this genetically modified crop.