Two 42-d floor pen studies of identical design were conducted to evaluate the efficacy of enzyme supplementation of broiler diets containing full-fat double zero rapeseed. In both trials, 300 1-d-old Ross 308 males were allocated randomly to two dietary treatments with 15 replicates (10 birds per replicate). The birds received two isonutritive diets, pelleted at 78°C. Diets were either not supplemented or supplemented with a commercial enzyme blend providing xylanase and p-glucanase. In general, in both trials the supplementation of carbohydrase improved bird performance, however, only in the second experiment the overall body weight gain and feed conversion ratio were significantly improved. The enzyme addition reduced (P<0.05) the concentration of serum insulin (0.75 vs 0.49 ng/ml), total cholesterol (4.35 vs 3.03 mmol/1) and its fractions, whereas no effect on the concentration of blood glucose was observed. No significant effect of the enzymes on the ileal digestibility of nutrients or on apparent ileal metabohzable energy was found; however, total tract fat digestibility and AMEn value tended to be higher following enzyme supplementation. (78.2 vs 73.8% and 12.6 vs 12.4 MJ/kg). The results of the present study suggest that carbohydrases supplementation may improve the nutritive value of full-fat rapeseed in broiler chicken diets.