Fungal contamination of agricultural products can prove to be harmful to humans and domestic animals as these fungi produce a variety of mycotoxins which can eventually occur in food. Acute intoxications with mycotoxins occur regularly in farm animals but, fortunately, are infrequently observed in humans. However, the chronic exposure of humans to mycotoxins occurs regularly. Such exposures are potentially teratogenic and carcmogenic and can suppress the immune system. It is presently impossible to establish safe levels of exposure for most mycotoxins due to scanty epidemiological data and insufficient observations on experimental animals. With respect to aflatoxin all available data point to a real health risk. Risk analysis based on epidemiological observations shows that the liver-cancer risk for individuals in South Africa is potentially increased by continued exposure to the present legally permitted level of aflatoxin in food.