Mycotoxins are a diverse group of secondary metabolites produced by moulds. They have a wide range of toxicological effects both in humans and animals. Nowadays about 200 of these metabolites have been described, but only a few of them may be considered as important from the agricultural point of view. In this publication, some aspects such as mycotoxin producing species, analytical methods, natural occurrence, preventive and detoxification techniques and regulations of these kind of mycotoxins will be developed by different authors involved in these research issues.