Six hard endosperm (modified) opaque-2 (o2) corn populations from CIMMYT were compared with local corn cultivars Diente de Caballo and Mayorbela. Grain yield, days to 50% anthesis, plant and ear height, endosperm modification, and lodging were measured. Diente de Caballo was very late in flowering, whereas Mayorbela was earlier than the mean of the o2 genotypes, Diente de Caballo and Mayorbela were taller than o2 genotypes; thus they were more susceptible to lodging. Diente de Caballo was higher yielding than o2 genotypes, but Mayorbela ranked among the lowest yielders at all locations. The· magnitude of the local x genotype variance suggests that multiple location testing would be needed to distinguish between yield and degree of modification of different genotypes. Other traits studied could be tested at one location.