Corn earworm, Helicoverpa zea Boddie, is a major pest of maize in the United States. Host plant resistance is widely considered a desirable method for reducing losses to this pest. Nine inbred lines were evaluated for resistance to ear damage, larval survival, and weight of larvae. Mp313E and Mp717 sustained less damage than the other lines, and larval survival and growth on these lines was reduced. Analysis of a diallel cross among the nine lines indicated that both general combining ability (GCA) and specific combining ability (SCA) were significant sources of variation in the inheritance of resistance to ear damage. GCA was also a significant source of variation in the inheritance of resistance to larval growth. GCA effects for reduced larval weight were significant for Mp313E and Mp717. These lines could be useful in the development of maize hybrids with corn earworm resistance.