Abstract: The study was conducted in order to measure the levels of Aflatoxin B1 (AFB1) in feedstuff by ELISA used by some of cattle farms in Amol (northern Iran). Out of 96 samples at 45 traditional and 51 semi-industrial cattle farms ones (concentrated feed, beet pulp and cotton meal) were selected in random basis during 3 different seasons of winter, spring and summer 2009. Out of 45 traditional samples, 20 samples (44.4%) and out of 51 semi-industrial samples, 22 samples (43.1%) showed AFB1 contamination more than the limit accepted by EU (5 μg kg-1). The contamination levels in concentrated feed, beet pulp and cotton seed were 58.8, 43.7 and 26.7%, respectively. The contamination level in winter, spring and summer were 56.4, 38.7 and 34.4%, respectively. Feedstuffs should be tested regularly in terms of AFB1 and if they were contaminated, it would be better not to use them.