Two experiments were conducted to investigate the impact of increasing dietary levels of whole barley (WB) with or without exogenous enzymes and of whole wheat (WW) without E fed from 7 d of age, on performance and carcass characteristics of broilers. Experiment 1 was conducted with corn-soybean meal grower diets containing WB at 0, 10, 10 + enzymes, 15, or 15% + enzymes. The finisher diets contained, as fed, WB at 0, 15, 20 + enzymes, 15, or 20% + enzymes. In Experiment 2, grower diets contained 0, 10, 10, 20, or 20% WW with 0, 20, 35, 20, or 35% WW in the finisher diets. No enzymes were used for WW diets. In each Experiment, 1,500 1-d-old Ross x Ross male broilers were randomly distributed in 30 floor pens of 50 birds each. Six replicates were allotted to each treatment. Body weight, average daily gain (ADG), feed intake (FI), and feed efficiency ratio (FER) were measured at 7, 21, and at 38 d of age. In Experiment 1, ADG was lower (P < 0.05) in the control vs. Diet 5. However, FER with enzyme addition was lower, and FI with enzymes was higher (P < 0.05). Final BW, gizzard, and pancreas weights were higher (P < 0.05) with WB inclusion. In Experiment 2, ADG and BW significantly increased with addition of WW, although the response was best for Diets 2 and 3. Abdominal fat and carcass weights increased (P < 0.05) with the WW levels in the diets.