Sucrase enzyme is an enzyme responsible for digestion and absorption of carbohydrates in the small intestine. Therefore, an experiment was conducted to study the effects of different levels of ZnO supplement on sucrase enzyme activity of the small intestine in male broilers from 1 to 42 days. On hundred eight male broiler chicks (Ross -308 strain) were randomly assigned into 3 groups with 3 replicates of 12 birds per group. Control group was fed base diet and other groups with the same base diet plus 50 or 100ppm ZnO. Broilers were slaughtered after 21, 28, 35 and 42 days and different segments of small intestine (at 1, 10, 30, 50, 70 and 90% of total length of the small intestine) were taken from each replicates (N=2). Results revealed that intake of ZnO supplement (100ppm) significantly increased sucrase enzyme activity at the age of 21, 28, 35 and 42 days at proximal small intestine mucosa in comparison with other groups (p<0.05).