In an episode of aflatoxicosis in feeder pigs, mortality was about 20%. Histopathologic findings characteristic of experimentally induced aflatoxicosis and the finding of aflatoxin B1 in the serum of pigs and in the cornbased feed confirmed the diagnosis. Aflatoxins B1 and B2 were found in the corn used to prepare the feed. Combine harvesting of the corn, which cracked a large percentage of the kernels, coupled with prolonged drying time of the corn probably contributed to the aflatoxin production. Although the corn was fed to adult swine without observable effect, 47 of the 250 feeder pigs developed typical signs of aflatoxicosis. Unseasonably cold weather apparently was a factor in initiating the onset of clinical signs and probably increased the severity of the disease.