Exogenous enzymes such as xylanase can cause recovery of efficiency in poultry. In this study we investigated the effects of xylanase supplementation on small intestine histomorphometry in broilers chicken. Two levels of xylanase supplementation (with or without 0.07% xylanase) was used in 4 treatment groups (two repetitions for each group and 15 chicks per group). After 42 days, 10 chicks from each pen were euthanized to study the duodenum, jejunum, and ileum histomorphometry. Using light microscope, morphological changes of small intestine including villous height, number of goblet cells, diameter of epithelium, crypt depth and ratio of crypt depth to villous height were evaluated. Addition of xylanase increased villous height and crypt depth (p<0.05) and decreased goblet cell number and epithelium diameter in different sections of small intestine as compared to the control group. The findings of this study suggest that addition of exogenous xylanase in broiler diets based on wheat can effectively increase the absorption of nutrients.