In the present work the possibility of chemical control of Aspergillus flavus to prevent the production of aflatoxin in peanuts, by spraying fungicides to the freshly-dug kernels in the windrow was studied. Four efficient fungicides (Ferbam, Thiram, Sodium Ortophenilfenate and Captafol) screened by tests "in vitro" were used in experiments run for four years in the regions of Caiabú, Campinas, Marilia, Pirapozinho and Ribeirão Preto. From the results the Authors concluded, within the range and conditions of this experiment, that when the harvest is carried in rainy periods the fungicides seem to be inefficient, and when rains are absent, the weather condition by itself seems to inhibit the growth of A. flavus and prevent the occurrence of aflatoxin. Nevertheless, the Authors suggest more studies on the subject.