Seventy-eight samples of farmer stock peanuts, representing peanuts grown in nine different geographical areas during 1964, were assayed for aflatoxin and examined for associated microflora. Only two samples contained more than 50 ppb of aflatoxin. Infestation by members of the Aspergillus flavus-oryzae group varied from 35 to 100% of the kernels per area and from 1 to 100% of the kernels per sample. Aflatoxin production by individual isolates ranged from 0 to 349,143 ppb under the test conditions employed. In general, the isolates produced 8 to 10 times more B1 than B2, and no isolate producing aflatoxins G1 or G2 was found. The importance of proper postharvest handling of peanuts is emphasized by the prevalence of isolates of A. flavus-oryzae capable of producing aflatoxins on farmers stock peanuts.