Wheat grains of grades No. 1, 2, 3 Northern were treated with 100, 300, 500, 700, or 1000 krad of 60Co gamma irradiation to study its effect on the fungi present. Species of Alternaria and Fusarium were abundant, and were highly resistant to irradiation in situ, requiring 1000 krad for complete inactivation. Species of Aspergillus, Rhizopus, and Absidia were less frequently isolated from the grain, and were less resistant to inactivation by irradiation. A dose of 300 krad was required to completely eliminate these fungi. The grade of grain did not effect the survival behavior of various fungi after treatment with gamma irradiation.Increasing doses of gamma irradiation interfered progressively with the formation of septa in the spores of Alternaria sp., and, at a dose of 700 krad, spores failed to form.