The discovery of aflatoxins began immediately after an outbreak of a disease of turkeys of unknown etiology in England in 1960. The disease was called Turkey "X" disease and was eventually attributed to a toxic groundnut meal imported from Brazil. From that point, an extensive effort to find the cause eventually elucidated that a species of mold, called Aspergillus flavus, was involved and the hepatotoxic products of this mold, found also as components in the toxic groundnut meal, were called aflatoxins. The finding that the aflatoxins were carcinogenic caused concern for their occurrence in human foods and led to worldwide efforts to determine the relationships of these carcinogens to human disease and determine their occurrence in human foods as well as in animal feeds. The findings that the aflatoxins were immunosuppressive resulted in establishing that they were probable underlying causes to other diseases, mostly infectious in nature. Subsequent efforts led to the finding that aflatoxins can occur preharvest and therefore the aflatoxins were no longer only a storage problem. Major crops such as corn, peanuts, cottonseed, and certain tree nuts were frequently found to be contaminated. These findings were cause for the aflatoxin problem to become a large multidisciplinary scientific investigation into various aspects of concern such as eradication, control, analysis, epidemiology, and plant pathology as well as major efforts to determine the nature of animal disease caused by the aflatoxins. Present-day investigations with aflatoxins continue with elimination as a major thrust based on knowledge of the biosynthetic pathway, genetics of both host and pathogen, host-parasite-vector interactions, plant breeding, biocontrol, and selected agronomic practices. Throughout this manuscript the use of the word aflatoxin(s) may imply a mixture of aflatoxins but usually refers to aflatoxin B 1 . However, where necessary the specific aflatoxin designation may be utilized.