Studies were carried out to detect the causal fungi that cause grain mold of Zea mays in different locations of Egypt. The most dominant fungi on maize grains could be arranged descendingly as Fusarium moniliforme, Nigrospora oryzae, Fusarium graminearum. Penicillium spp.. Aspergillus niger, Aspergillus flavus. Helminthosoprium spp. Rhizopus sp. Mucor sp, and Alteraara spp. Also, the effect of storage period, grain moisture content and temperature of storage on the ability of F. moniliforme and N. oryzae to attack maize grains was studied. The severity and percentage of infection by the tested fungi increased by increasing moisture content and storage time. Prolonging storage periods at 18°C, generally resulted is reducing the weight of both the germ and hull in either healthy or grains infected with N. oryzae, whereas no difference occurred when the grains were infected with F. moniliforme. Also, the corn attacked by the tested fungi showed a marked increase in free and total phenols. Such increase was parallel to the increase in grain moisture content and prolonging storage time.