International audience ; Beer was chosen as a cereal-derived and homogeneous product allowing to compare the organic and conventional production modes in terms of mycotoxin contamination levels. Ochratoxin A (OTA, a storage mycotoxin) and deoxynivalenol (DON, a field mycotoxin) were assessed by HPLC methods in organically and conventionally produced beers sold in Belgium. Immunoaffinity column (OchraTest® and DONPrep®) purification was used prior to HPLC analysis. For in-house validation, recovery experiments carried out with the spiked beers in the ranges of 50 - 200 ng OTA l-1 and 20 - 100 µg DON l-1 led to the overall averages of 91 % (RSD = 10 %, n =9) and 93 % (RSD = 5 %, n = 27), respectively. Organic beers collected during 2003-2004 tended to be more frequently OTA contaminated (95 %, n = 40) than their conventional counterparts (50 %, n = 40). Conventional beers were OTA contaminated at a mean concentration of 25 ng l-1 (range: 19 - 198 ng l-1) whilst organic beers contained a mean level of 182 ng l-1(range: 18 - 1134 ng l-1). High OTA contamination above the limit of 200 ng l-1 (up to 1134 ng l-1) occasionally occurred in organically produced beers. A complementary survey performed with the same brands in 2005 did not confirm this accidental presence of excessive OTA loads (range: 3 - 67 ng l-1 for 10 conventional beers and 19 - 158 ng l-1 for 10 organic beers). Establishing a maximum of 3 µg OTA kg-1 in malt, the application of the regulation EC 466/2001 (entered in force before the last sampling) may be related to the improvement observed. The overall incidences of DON were 67 and 80 % in conventional and organic beers, respectively. DON concentrations ranged from 2 to 22 µg DON l-1 (mean = 6 µg DON l-1) in conventional beers whilst organic beers were contaminated from 2 to 14 µg DON l-1 (mean = 4 µg DON l-1). DON in beers does thus not appear to be a major matter of concern. From the statistical tests, it could be concluded that the variation between different batches was significant (p < 0.0001) ...