This experiment was conducted to compare the effects of prebiotic as alternative feed additive to an antibiotic growth promoter (bacitracin methylene disalicyate) on the growth performance and morphometrical parameters of the small intestine of broiler chickens. One hundred and forty four day old broiler chicks were randomly assigned to one of three dietary treatments for 6 wk and each treatment contained four replicates (12 birds each). Dietary treatments were as follow: 1- Control (basal diet), 2- basal diet + antibiotic growth promoter and 3- basal diet + prebiotic. During the feeding experimental period, body weight, weight gain, feed intake and feed conversion ratio were measured. At the end of the experiment, small intestine segments were sampled and routine histological laboratory methods containing fixation, dehydration, clearing and paraffin embedding were used. Sections stained with haematoxylin and eosin for light microscopy evaluation and the height and width of villi and depth of crypts were measured. The results showed that body weight, weight gain and feed conversion ratio were not affected by dietary treatments. Prebiotic and antibiotic had significant (P < 0.05) effect on improvement of feed intake in 22 - 42 days and total period compared with the control. The addition of prebiotic or antibiotic increased the villus height in duodenum (P < 0.05) and prebiotic increased villus width of duodenum and ileum compared with other treatments. The duodenal crypt depth was increased by antibiotic compared with the prebiotic and control group. In conclusion, prebiotic can be used as a suitable alternative to antibiotic growth promoter.