The natural occurrence of fungal contamination was evaluated in stored maize in three different agro-ecological zones (Iran, Brazil, and China). A total of 45 samples were analyzed and 685 fungal isolates were identified. The most frequent isolated fungi from maize originated from Iran, Brazil, and China were Fusarium sp. (17.3, 17.9, 37.1%), Aspergillus sp. (9.3, 17.4, 19.7%), Penicillium sp. (5.8, 15.2, 17.6%), Rhizopus sp. (2.4, 3.2, 3.5%), Mucor sp. (1.1, 1.6, 1.3%), Cladosporium sp. (1.6, 1.9, 1.9%), Alternaria sp. (1.1, 1.6, 1.3%), Geotrichum sp. (0, 0, 0.3%), Acromonium sp. (0.5, 0.8, 0%), and Absidia sp. (0, 0.8, 0.5%), respectively. Significant difference was observed between the frequency of fungal isolates of Iranian maize and foreign products (P<0.0005). Maize mycoflora profiles showed that Fusarium verticillioides and Aspergillus flavus prevailed in 30.7 % and 13.3 % of the samples from China, in 12 % and 5.3 % of the samples from Iran, and 11.7 % and 11.5 % of the samples from Brazil, respectively. There were significant differences in the frequency of Fusarium verticillioides in Chinese maize with other countries products (P<0.0005) and that of Aspergillus flavus in Iranian maize with other countries (P<0.002). The results emphasize that farmers and consumers should be alerted to the danger of fungal contamination in maize.