In the present work, the occurrence of aflatoxins B and G as well as a possible correlation between both were studied in 48 samples of peanut flour from 8 oil mills of the region Noroeste, in the State of São Paulo. The samples were obtained in four collections representing material from two crops in two different seasons: March and May in the rainy season and July and September in the dry season. From the results it was concluded that: a) the occurrence of aflatoxin was generalized in that region, for all the samples were toxic; b) the toxicity level was found to be very high (figures from 0.1 to 20.0 ppm) being higher in the rainy season average of 4.34 ppm, against 1.83 ppm in the dry season; c) it was considered that only 8.33% of the material examined could be utilized for admixturing in feedstuffs; d) it was found a weakly positive correlation, not statistically significant, in the production of the aflatoxins B and G.