Ochratoxin A (OA) is produced mainly by Penicillium verrucosum, Aspergillus ochraceus and A. carbonarius and it was found as a contaminant in the large number of agricultural commodities, feedstuffs and animal organs such as kidney and liver of pig. Toxicological studies indicated that OA is a teratogenic, mutagenic and carcinogenic mycotoxin with the strong toxic effects on liver and kidney. In some endemic areas in the world, OA was suspected to be related to swine nephropathy and has been detected in blood samples from inhabitants in these areas as well. More and more attention was paid to the relationship between the consumption of food contaminated with OA and human health. In this paper, OA--producing fungi, the contamination of it to the agricultural commodities, its toxicity and risk assessment are reviewed.