The European corn borer (ECB), Ostrinia nubilalis (Hubner), major pest of maize (Zea mays L.) in Central Europe. In order compare transgenic Bt maize hybrids with their non-transgenic counterparts and commercial hybrids, field trials and a laboratory bioassay were conducted. The field experiments were performed at four locations with natural and manual infestation of ECB larvae in 1998 and 1999. Transgenic Bt hybrids showed significantly lower means than their corresponding non-transgenic counterparts and commercial hybrids for all resistance traits (damage rating of stalks, number larvae per plant, and percentage of damaged plants or ears under infestation). Bt hybrids containing the CryIA(b) gene under control of green tissue and pollen-specific promoters (event 176) showed a significantly higher percentage of damaged ears than hybrids carrying the CryIA(b) gene under the control of a constitutive promoter (Mon810). Bt and non-Bt hybrids showed no significant differences for all agronomic traits, except for plant height under insecticide protection and grain yield reduction under infestation, whereas Bt hybrids had significantly lower means than their nontransgenic counterparts and other commercial hybrids. All resistance traits were significantly correlated with grain yield reduction. laboratory bioassay confirmed the level of antibiosis of Bt hybrids against neonate ECB larvae. Bt hybrids showed the highest level ECB resistance and therefore are an attractive method of preventing ECB damage within an integrated pest-management system.