Progress in understanding the biology of Aspergillus has greatly improved with the new techniques in genome sequencing and the developed molecular tools that enable rapid genetic analysis of individual genes. Particularly, the genetics of aflatoxin synthesis is regarded as a model to gain insight into fungal secondary metabolism. This compilation discusses topics that include the prevalence of aflatoxin B1 in cereals; contamination exposure, toxicology and control of aflatoxins in food and feed; immunosuppressive actions of aflatoxin; hazards and regulations; toxicological effects, risk assessment and legislation for aflatoxins; and the threat aflatoxins have on the economy and health.