This study was conducted to investigate the effect of dietary soy isoflavone (ISF) on growth performance, ileal nutrients digestibility and intestinal morphology of broiler chickens. A total of 240 mixed sex day-old Ross 308 chicks were allocated to 4 treatments with 3 replicates of 20 birds each. The birds were fed with corn-soybean based diet supplemented with either 0 (control), 25, 50 or 100 ppm ISF for a period of 21 days. Intestinal content and tissue samples were collected on day 21. During the experimental period, dietary supplementation with ISF had non-significant effect on feed intake, while improved weight gain and feed conversion ratio (P<0.01). Supplementation of 50 and 100 ppm ISF significantly (P<0.01) increased ileal digestibility of dry matter, protein and fat. Ileal digestibility of energy was increased at 50 ppm ISF (P<0.01). Jejunal villus height and surface area, and villus height to crypt depth were increased (P<0.01) whereas crypt depth was decreased (P<0.05) by 50 or 100 ppm ISF supplementation. Relative weight of pancreas decreased due to additional 25 and 50 ppm ISF (P<0.05). Findings of this study showed the beneficial effects of supplemental ISF on performance and digestive function of broilers. The level of 100 ppm soy ISF can be recommended for use in chicken diets.