Sportak is a protective and contact effective fungicide with active ingredient of prochloraz (450 g/L). It prevents germination in fungi and stops growth of micelial. It belongs to the group of fungicides which inhibits sterol biosynthesis. It inhibits the biosynthesis of giberellin in plants and leads to a slowdown in growth and also causes genotoxicity. The cytological and genotoxic effects of different concentrations of Sportak (5 ml/L, 10 ml/L and 20 ml/L) on corn (Zea mays) were investigated on the basis of the concentration applied to the field. Cytological observations showed that the mitotic frequency in root meristematic cells decreased and abnormality freque cy increased in all concentrations of Sportak. 20 RAPD (Random Amplified Polymorphic DNA) primers were used. Genomic template stability changed in RAPD profiles at various Sportak concentrations. Sportak had inhibitory effect on mitosis of Z. mays and also caused polymorphism in plant genome.