An experiment was conducted to investigate the effect of dietary supplementation of xylo-oligosaccharides (XOS) on growth performance, meat quality, immune functions, duodenal morphology and intestinal microbial populations of broilers fed a conventional corn-soybean meal basal diet. A total of 450 1-day-old commercial Arbor Acres male broiler chicks were randomly allocated by bodyweight to 1 of 5 treatments with 6 replicate cages (15 broilers per cage) for each of 5 treatments in a completely randomized design. Chicks were fed the basal corn-soybean meal diets supplemented with 0, 25, 50, 75, or 100 mg of XOS kg–1 of diet, respectively, for an experimental duration of 42 days. The results showed that supplementation of XOS affected feed conversion rate (feed/gain, F/G) during days 22–42 and 1–42 (P<0.03), drip loss in thigh muscle (P=0.02), and duodenal crypt depth (P=0.005) on day 42, but had no effect (P>0.05) on all other measured indices. The chicks fed the diet supplemented with 100 mg of XOS kg–1 had the lowest (P<0.05) F/G and drip loss in thigh muscle. The drip loss in thigh muscle decreased linearly (P=0.003) as the supplemented XOS increased. Duodenal crypt depth decreased (P<0.05) at the supplemental level of 75 mg of XOS kg–1. The results indicate that dietary supplementations of 75 and 100 mg of XOS kg–1 are beneficial to broilers fed a conventional corn-soybean meal diet.