This study was conducted to determine the effect of spearmint (Mentha spicata) on productive and physiological performance of broiler chicks. One hundred and eighty day old unsexed (Arbor Acres) broiler chicks were used in this experiment. Birds were distributed randomly into four equal treatment groups, in three replication, 15 chicks each. The dietary treatments including T1(control diet), T2 with addition 0.5% spearmint, T3 with addition 1% spearmint and T4 with addition 2% spearmint. Feed and water were provided ad-libitum. Body weight, body weight gain, feed consumption and feed conversion ratio were weekly recorded. At the end of the experimental period (42 days of age), three birds were randomly chosen to determine both hematological and blood biochemical parameters and carcass traits. The results indicated that the addition of 0.5 and 1% spearmint did not significantly (P>0.05) affect final body weight, total gain compared with the control group, while the supplementation of different levels of spearmint to the diets of broiler chicks improved feed conversion ratio, also there was significant differences between the control group and the groups treated with different spearmint levels on feed consumption. The chickens fed diet supplemented with 2% spearmint had significantly lower body weight, total gain and feed consumption compared to the control group and the other treatments. There were an increase numerically in Hb concentration and red blood cell count in chickens fed diet supplemented with 2% Spearmint compared to the control group and the same group had lower significantly in the total cholesterol compared with the control group and the other groups. Chickens fed diet supplemented with 1% Spearmint had significantly higher concentration of total plasma lipid. There were no significant differences in carcass traits between the control group and the groups supplemented with 0.25, 0.5, and 1% spearmint in chicken diet. There was a significantly higher superoxide dismutase (SOD) activity in group treated with 2% Spearmint. Meanwhile, the chicken supplemented with 1% Spearmint had higher significantly total antioxidant capacity (TAC) compared with the control group and the other treated groups.