The mycotoxin ochratoxin A (OTA) has been linked to the genesis of several disease states in both animals and humans. It has been described as nephrotoxic, carcinogenic, teratogenic, imunotoxic, and hepatotoxic in laboratory and domestic animals, as well as being thought to be the probable causal agent in the development of nephropathies (Balkan Endemic Nephropathy, BEN and Chronic Interstitial Nephropathy, CIN) and urothelial tumours in humans. Ochratoxin has been suggested to mediate its toxic effects via induction of apoptosis, disruption of mithocondrial respiration and/or the cytoskeleton, or, indeed, via the generation of DNA adducts. Thus, it is still unclear if the predominant mechanism is of a genotoxic or an epigenetic nature. Ochratoxins have been overshadowed by better known mycotoxins, as data regarding their existence and toxicity are less relevant than for the other mycotoxins (ergot alkaloids, aflatoxins). However, in January 2006, the owner of a major Italian grain mill was arrested and charged with importing Canadian wheat contaminated with ochratoxin A. Key questions in the ochratoxin story are still not completely answered, especially in the areas of biosynthesis, contamination of crops, toxicity and epidemiology regarding this mycotoxin. The intention of this review is to collate and discuss the currently available data on OTA-mediated toxicity with particular accent on their relevance for the in vivo situation and also to focus upon the importance of data regarding the contamination of foods.