A study of the effect of adding lemon balm leaves and their extract on physiological performance and immunological traits of Ross308 broiler chickens. 300 broiler chicks were used, were randomly distributed to five groups, as follows: T1: (control treatment without any treatment). T2: adding Melissa officinalis L. leaves powder at a concentration of 5 gm / kg of feed. T3: adding the water extract of Melissa officinalis L. leaves at a concentration of 5 ml extract / liter of drinking water. T4: adding the oil extract of Melissa officinalis L. leaves at a concentration of 5 ml of oil / kg of feed. T5: adding alcoholic extract of Melissa officinalis L. leaves at a concentration of 5 ml of oil / kg of feed. The results indicated that all treatments of adding Melissa officinalis L. leaves powder improved the blood and immunological characteristics of broiler chickens, and that the best results were the use of water extract of melissa leaves powder compared to the rest of the treatments.