This document specifies a procedure for the determination of five Alternaria toxins in wheat, tomato puree and sunflower seeds by high-performance liquid chromatography (HPLC) coupled with tandem mass spectrometry (MS/MS). The method has been validated with both naturally contaminated and spiked samples of wheat, tomato puree and sunflower seeds. Validation levels for altenuene (ALT) ranged from 2,18 ¼g/kg to 13,8 ¼g/kg. Validation levels for alternariol (AOH) ranged from 1,82 ¼g/kg to 46,7 ¼g/kg. Validation levels for alternariol monomethyl ether (AME) ranged from 1,29 ¼g/kg to 47,2 ¼g/kg. Validation levels for tentoxin (TEN) ranged from 5,29 ¼g/kg to 218 ¼g/kg. Validation levels for tenuazonic acid (TEA) ranged from 41,8 ¼g/kg to 1 618 ¼g/kg. Limits of quantification of 1 ¼g/kg for ALT (except in wheat and sunflower seeds), AOH and AME; 5 ¼g/kg for TEN and 10 ¼g/kg for TEA or lower are achievable using this method.