Mycotoxicoses occur as a result of consumption of feed contaminated with the toxic metabolites and fungi. Over 200 mycotoxins have been described. Mycotoxic fungi are responsible for significant financial losses encompassing a broad spectrum of crop and animal agriculture and extending through the food chain to the consumer. Crop farmers are impacted by the field-borne, intermediate and storage fungi. Contamination of successive stages in the growing cycle and subsequently during the storage result in destruction and downgrading of grains and peanut meal as well as depressing nutritional value. Mycotoxins lower the profitability of animal production through decreased growth, feed conversion efficiency, liveability and reproductive potential. Mycotoxin residues are responsible for the destruction of contaminated milk and dairy products. Producers and consumers in the rural areas and tropical countries are especially vulnerable to acute toxicity and to the long term mutagenic and immunosuppressive effects of mycotoxins which excerbate primary infections or interact with intercurrent diseases.