Ochratoxin A (7-L-β-phenylalanylcarbonyl-5-chloro-8-hydroxy-3,4-dihydro-3-R-methylisocoumarin) was first isolated in 1965 from A. ochraceus. Meanwhile several Aspergillus and Penicillium species are known to produce ochratoxin A. The toxin frequently occurs as a contaminant in plant products worldwide, predominantly during storage. Numerous papers have described its occurrence in, for example, cereals, beans, coffee, grapes, beer, and red wine. In particular for Penicillium spp., cocontamination with ochratoxin A and other Penicillium toxins, such as citrinin, is quite common.