This chapter identifies animal diseases that are host specific and reviews the effects of various human diseases on animals. It also identifies history, etiologic, human Infection, diagnosis, public health aspects and therapeutic aspects of each disease important to epidemiology and prevention. Well-known mycotoxicoses include aflatoxicosis, alimental toxic aleukia, ergotism, fusariotoxicosis, facial eczema, hyperestrogenism, leukoencephalomalacia, mycotoxic nephropathy, ochratoxicosis, porcine pulmonary edema, and stachybotryotoxicosis. The occurrence of mycotoxins in stored feed commodities and mixed feeds that are shipped in quantity to distant and foreign markets substantially diminishes the concept of regional and seasonal exacerbations of mycotoxic disease. Clinical mycotoxic disease in animals or humans is a result of changes in basic biochemic effects induced by mycotoxins. Ochratoxin and citrinin may be involved singly or in combination in causing mycotoxic nephropathy in swine and possibly in humans. Changes in lipid metabolism caused by mycotoxins include reduced fatty acid and cholesterol biosynthesis, reduced pancreatic lipase, and altered sphingolipid synthesis.