We revealed a total of 398 gut genes differentially expressed (i.e., either up- or down-regulated genes with expression ratio ≥2.0) in S-strain larvae, while only 264 gut genes differentially expressed in R-strain larvae after fed transgenic corn leaves. Although the percentages of down-regulated genes among the total number of differentially expressed genes (199 genes or 50% in S-strain; 119 genes or 45% in R-strain) were similar between the R and S-strains, the expression ratios of down-regulated genes were much higher in S-strain than in R-strain. These results imply that R-strain larvae had an increased ability to deal with transgenic corn as compared with S-strain larvae. We also revealed that 17 and 9 significantly up- or down-regulated gut genes from S- and R-strain larvae, respectively, including serine proteases (trypsins and chymotrypsins) and aminopeptidases. Overall design: Trangenic corn induced gene expression was measured in O. nubilalis resistant and susceptible strains' gut at 6-hrs after transgenic corn feeding. Three independent experiments were performed using three insect gut samples ,and each sample was from five insects' gut pooled.