The corn (Zea mays, L.) isoinbreds with gene Ht₁ were obtained from backcross method in which corn inbreds with different resistance to the corn leaf blight and those with the gene Ht₁A were used asrecurrent parents and the resistant resource,respectively.Application ofthe monogenic resistance in corn prcduction was analyzed on the basis of the lesion numbers, the lesion size and the spore numbere. It was shown that the lesion numbers of the mid-susceptible corn inbreds with the transformed Ht₁A was not reduced but the lesion size and thespore numbers was significantly decreased. It was suggested thatthe monogenic resistance was useful to contrell spore numbers and to delay the desease prevalence in corn prcduction.