The purpose of this paper was to evaluate the administration of antibiotics and probiotics to broiler chickens and to determine the contribution of probiotics to the prevention of Salmonella typhimurium infection in Ross broiler hens. Chicks (250) Three groups of 50 one-day-old Ross broilers each contained 50 chicks: G1, G2, and G3 (50 chicks). negative management (non infected and non treated chicks). G2 (50 chicks) infected by S. typhimurium (109 CFU) were administered Gentamycin and colistin sulphate at one age old for five days at a dose of 0.5 gm/25 litres of drinking water. G3 (100 chicks) infected by S. typhimurium (109 CFU) were given probiotics (Guardizen M) mixed probiotics concentrate 5.6 g (1x1010 CFU) of Lactobacillus plantarum, Lactobacillus acidophilus, Lactobacillus rhamnosus, Lactobacillus bulgaricus, and Bifidobacterium bifidum. It was supplementary to the water for five days in a row. After infection, the experiment's time frame was extended by three weeks. Results showed that g G3 had