Maize (Zea mays L.) is one of the important food crops for human and animal in Egypt as well as in the world. Current study was conducted to isolate and identify pathogen of leaf spot of maize from the infected tissue. Infected and healthy plants were also analyzed for various biochemical changes. Examination using image analysis system revealed thin and disrupted epidermis at stoma, with large size of subsidiary cells and presence of vacuoles in infected leaves. Drechsleara dactylidis was isolated from the diseased maize plants. Contents of chlorophyll a and b were significantly decreased, while activity of both catalase and peroxidase were significantly increased in diseased plant. Amino acids such as phosphoserine, glycine, citrulline, cystine, leucine, tyrosine and phenylalanine were decline, whereas ß-alanine and ß-amino iso-butyric acid were increased in infected plant tissue. Salicylic acid determined through HPLC found to be accumulated 2-folds and proteins expression assessed by SDS-PAGE was enhanced in infected tissue.