The natural occurrence of aflatoxins B-1, B-2, G(1) and G(2), incidence of Aspergillus falvus, and capacity to produce aflatoxins by A. flavus isolates, were investigated in 100 corn-based samples from Spain destined for human and animal consumption. Only one sample for animal consumption and none for human consumption were found to be contained with aflatoxins B-1 and B-2. The levels of contamination were 0.15 mu g/g of B-1 and 0.08 mu g/g of B-2. Of 43 isolate of A. flavus, only 4 were aflatoxin producers.