Trichothecenes are tricyclic sesquiterpenes, divided in type A and B according with the absence/presence of a cheto group at C-8 of the epoxide ring. They are natural contaminants of cereals, and constitute the largest group of mycotoxins produced by Fusarium. The most common trichothecene type B in cereals is deoxynivalenol (DON), mainly produced by F. graminearum, and F. culmorum. Among trichothecenes type A, T-2 and HT-2 toxins are most harmful compounds produced by Fusarium species, mainly F. sporotrichioides and F. langsethiae. The trichothecenes are potent inibithors of proteic synthesis. Deoxynivalenol is the most common contaminant of cereals and also commonly known as vomitoxin. The commercialization of food commodities contaminated by DON is subjected to legal limits regulated by European Commission in cereals and by-products, while limits for T-2 and HT-2 toxins are only recommended.