This study was conducted in the poultry field of the Animal Production Department, in College of Agriculture, University of Kirkuk, for the period from 1/9/2024 to 24/11/2024 for a period of 84 days, with the aim of studying the effect of using celery seeds as a natural antioxidant with the industrial antioxidant Butylated Hydroxy Toluene (BHT) on the productive and physiological performance of LOHMANN BROWN laying hens. 128 laying hens, 86 weeks age, were used. The birds were randomly distributed into 8 nutritional treatments, with 4 replicates for each treatment, and each replicate had 4 hens. The nutritional treatments were as follows: First treatment: Control feed free of celery seed additives and BHT, The second treatment: Adding 100 mg/kg of the synthetic antioxidant BHT,Third treatment: Adding 1% of celery seeds, Fourth treatment: Adding 1.5% of celery seeds, Fifth treatment: Adding 2% of celery seeds, Sixth treatment: Adding 1% of celery seeds with the addition of 100 mg/kg of the synthetic antioxidant BHT, Seventh treatment: Adding 1.5% of celery seeds with the addition 100 mg/kg of the synthetic antioxidant BHT, Eighth treatment: Adding 2% celery seeds with 100 mg/kg of the synthetic antioxidant BHT, At the end of the nutritional study, blood samples were taken from the jugular vein of the 12-weeks-age chickens to conduct chemical blood analyses and some production traits. The results of the study showed a significant superiority (P≤0.05) of the eighth treatment over the control treatment in terms of egg production, egg mass, and feed conversion ratio. As for the blood chemical characteristics, there was a significant improvement (P≤0.05) in the level of glucose (mg/dl), cholesterol (mg/dl), high density lipoproteins mg/dl (HDL) and low density lipoproteins mg/dl (LDL), while there were no significant differences in the concentration of total protein (g/dl) and albumin (g/dl) in blood