A genetically modified maize (Zea mays L.) line that contains the Optimum GAT trait (event DP-Ø9814Ø-6; 98140) was produced by integration of the gat4621 and zm-hra genes. The expressed GAT4621 and ZM-HRA proteins confer tolerance to the herbicidal active ingredient glyphosate and acetolactate synthase-inhibiting herbicides, respectively. The objective of this study was to compare the nutritional performance of 98140 maize grain to nontransgenic maize grain in a 42-d feeding trial in broiler chickens. Diets were prepared using grain from untreated 98140 plants and from plants treated with an in-field application of herbicides (98140 + Spray). For comparison, additional diets were produced with maize grain obtained from the nontransgenic near-isogenic control (control) and nontransgenic commercial reference Pioneer brand hybrids 33J56, 33P66, and 33R77. Diets were fed to Ross x Cobb broilers (n = 120/group, 50% male and 50% female) in 3 phases: starter, grower, and finisher containing 58.5, 64, and 71.5% maize grain, respectively. No statistically significant differences were observed in mortality, growth performance variables, or carcass and organ yields between broilers consuming diets produced with maize grains from unsprayed or sprayed 98140 and those consuming diets produced with near-isogenic control maize grain. Additionally, all performance and carcass variables from control, 98140, and 98140 + Spray test maize treatment groups were within tolerance intervals constructed using data from reference maize groups. Based on these results, it was concluded that 98140 maize grain (unsprayed or sprayed with a herbicide mixture) was nutritionally equivalent to nontransgenic control maize with comparable genetic background.