The primary emphasis of this study is to identify and characterize QTLs for resistance to northern leaf blight (NLB), one of the most important corn diseases in tropical and temperate environments. Second, the concept of multiple disease resistance (MDR) is being explored in order to help farmers reduce their loss to a range of diseases. A large number of disease QTLs have been mapped in the maize genome, and clusters of QTLs for various diseases were identified in some chromosomal regions. This and other evidence suggests the existence of loci that condition MDR. We used HIFs derived from MDR maize lines to analyze disease QTLs, focusing on regions of the genome associated with MDR.