Technical Abstract: Mycotoxins are mold poisons; aflatoxins are the best known and most widely studied mycotoxins. The contamination of foods and feeds with aflatoxin can have serious consequences for human and animal health. In general, aflatoxin exposure is most likely to occur in developing countries where food handling and storage processes are suboptimal, where malnutrition is widespread, and where few regulations exist to protect exposed populations. Fundamental studies on the genetics, biosynthesis, and molecular biology of aflatoxin producing fungi may offer insights into controlling this serious agricultural problem.