This study was performed with growing chickens (4 to 22 d of age) to evaluate the effects of feeding a rye-based diet supplemented with commercial enzyme preparation containing xylanase and beta-glucanase (Quatrazyme HP, Nutri-Tomen, France) on small intestine wall morphology, bile acid composition, nutrient digestibility, and bird performance compared with unsupplemented rye- or corn-based diets. The rye-based diet decreased (P < or = 0.05) weight gain, feed intake, and feed efficiency and increased water intake compared with the corn-based diet. Moreover, rye consumption reduced crude fat and protein digestibility as well as apparent metabolizable energy (P < or = 0.05). The small intestine wall showed that villus length, width, and surface were decreased in broiler chickens fed the rye-based diet compared with those fed the corn-based diet. However, crypt morphometry parameters were not affected by diet type. The concentration of conjugated bile acids in the small intestine contents of broiler chickens fed the rye-based diet was decreased (P < or = 0.05) compared with those fed the corn-based diet. These findings suggest that feeding a rye-based diet reduces villus capacity for nutrient absorption and bile acid capacity for fat solubilization and emulsification, resulting in decreased bird performance. The addition of xylanase and beta-glucanase to the rye-based diet improved (P < or = 0.05) weight gain, feed intake, and feed efficiency, and decreased water intake. The digestibility of nutrients and apparent metabolizable energy were also increased (P < or = 0.05). Addition of xylanase and beta-glucanase increased (P < or = 0.05) villus size and the villus height-to-crypt depth ratio, as well as the concentration of conjugated bile acids (P < or = 0.05) in the small intestine contents. Exogenous enzymes improved nutrient digestibility and broiler chicken performance, probably by improving the absorption capacity ofthe small intestine through increased villus surface and intestinal concentration of conjugated bile acids.