The experiment was conducted in the Department of Pharmacology and Department of Physiology, Faculty of Veterinary Science, Bangladesh Agricultural University, Mymensingh. Preparation of Poultry House for Experimental Birds: The experimental animal house particularly floor, walls, wire net, ceiling etc. were properly brushed with broom and then washed by forced water using a hosepipe. After washing with clean water, the room was disinfected by bleaching powder. Then the house was left for 7 days and then the shed was again disinfected with Virkons (Antes International Limited, England). The house was also fumigated by formalin and potassium permanganate for a period of 24 hours for disinfection. Rearing of Experimental Birds: A total of 350 day old commercial broiler chickens (Hubbard Classic) of both sexes were collected from a local breeder farm. The chicks were housed in floor pens containing litter composed of rice husk and saw dust and received a corn-based starter diet. The chicks were reared under fluorescent lighting. Chicks had access to feed and water ad libitum. All chicks were weighed individually at day 1, 7, 14, 21, 28, 35 and 42.The light was continuous during the experiment. The temperature was gradually decreased by 50 F at every week from 900 F to 750 F and continued throughout the experimental course. Chickens were reared under standard management conditions throughout the experimental course. Ranikhet and Infectious Bursal disease vaccine were administered accordingly. The overall management of rearing was well organized in order to prevent cross contamination effectively throughout the experimental course. Use of Lead Acetate and Garlic (Allium sativum) in Different Treatment Groups: The chicks were randomly divided to five (05) separate pens named Group T0, Group T1, Group T2, Group T3 and Group T4, consisting of 70 birds in each group. Group T0 was kept as control group. Group T1 was given only lead acetate @ 100mg/kg. Group T2 was treated with lead acetate @ 100 mg/kg + 1% garlic supplement. Group T3 was treated with lead acetate @ 100 mg/kg + 2% garlic supplement and Group T4 was treated with lead acetate @ 100 mg/kg + 4% garlic supplement. The experimental course was operated for 42 uninterrupted days. Three experimental diets were formulated to have 1%, 2% and 4% garlic powder for Group T2, Group T3 and Group T4, respectively. Control group diet was free from both dietary garlic and lead acetate. Broiler feed was formulated from the locally commercially available ingredients. Garlic was prepared without skin and dried in a Freeze Drier for 72 hours, and then ground to make powder. Ten (10) birds were sacrificed from each group on every week at Day1, Day7, Day14, day21, day28, day 35 and Day42. Analytical grade lead acetate that used in this study was obtained from Merck Company (Germany). Garlic was purchased from local market. The doses of lead acetate and garlic were based on previous studies (Hanafy, et al., 1994; Ashour et al., 2000; Vengris, 1974 and Yassin, et al., 2005). The garlic powder was not deodorized. Collection of Blood and Sampling Procedures: Collected blood samples were used for hematological analysis at 1st, 7th, 14th, 21st, 28th, 35th and 42nd day. At each sampling date, ten chickens were randomly sacrificed from each group. Approximately 2-3ml of blood samples was collected from wing vein into a screw cap test tube containing ethylene-diaminetetra-acetic acid (EDTA) by sterile disposable syringe immediately before the sacrifice of the chickens for hematological study. The whole blood samples having EDTA were stored at 40C and processed within 2 hours. The hematological analyses were performed according to Jain (1986). Estimation of Biochemical parameters: Blood samples were collected for biochemical analysis at 1st, 7th, 14th, 21st, 28th, 35th and 42nd day. At each sampling date, ten chickens were randomly sacrificed from each group. Having no anticoagulant, approximately 2-5 ml of blood was collected in a screw cap test tube for biochemical analysis with the aim for determination of biochemical parameters in lead toxicity induced broilers chickens. All kits required for the biochemical analysis were obtained from RANDOX Laboratories Ltd., Ardmore, Diamond Road, Crumlin, Co. Antrim, UK. The considered biochemical parameters operated in the present study was ALT, AST and Cholesterol. Then result was recorded from Reflectron® (Imahnheim, Boehringer, Germany) display. Statistical Analysis: The statistical analyses of variance were analyzed by Duncan’s Multiple Range Test (DMRT) using the General Linear Models (GLM) procedure of SAS software. Duncan’s multiple range tests were also used to locate the calculated means that are significantly different. Results were displayed as means ± standard error (SE).