Chronic effects of aflatoxins may be reducing the efficiency of swine production unit by decreasing the immune response leading to increased susceptibility to disease and increased mortality, and decreasing resistance to stress. The individual pig's response to aflatoxin is affected by many factors, but age is especially important with the younger pig much more susceptible to damage than older pigs. The greatest problem with aflatoxins in the United States appears to be in the Southeast and is associated mostly with corn and cottonseed meal. Management factors are important in the prevention and reduction of aflatoxins in feed. A simple quantative test for aflatoxins has been developed for field surveys of suspected feed and a decontamination process has also been developed.