Maize and sorghum grain samples (250g) exposed to 2.5, 5.0, 7.5 and 10.0 kGy of gamma irradiation and samples were evaluated for the per cent incidence of Fusarium species and level of fumonisins at regular intervals of 0, 30, 60, and 90 days of storage. The results revealed that, on 0 day the incidence of Fusarium species was 48 and 38% in respective maize and sorghum samples and there was gradual decrease in the incidence of Fusarium species at 2.5 and 5.0 kGy doses of gamma irradiation after 30, 60, and 90 days storage. The incidence of Fusarium species was zero in samples treated at 7.5 kGy and 10.0 kGy doses of gamma irradiation. In contrast, there was gradual increase in the incidence of Fusarium species in unirradiated maize and sorghum samples. Further, analysis of maize and sorghum samples by HPLC revealed that, on 0 day the fumonisin concentration was 0.95 µg/g and 0.49 µg/g respectively. After 90 days of storage, the concentration of fumonisin was 0.98 µg/g and 0.56 µg/g in respective unirradiated maize and sorghum samples. The fumonisin content in irradiated samples was 0.94 µg/g in 2.5 and 5.0 kGy, 0.93 µg/g in 7.5 kGy and 0.89 µg/g 10.0 kGy and 0.56 µg/g in 2.5 kGy, 0.54 µg/g in 5.0 kGy, 0.53 µg/g in 7.5 kGy and 0.52 µg/g 10.0 kGy respectively. The study revealed that, 7.5 and 10 kGy gamma irradiation treatments were successful in preventing the growth of Fusarium species on maize and sorghum samples however, irradiation did not appear to be an effective method for eliminating fumonisins.