A total of 480 samples (broiler cloacal swabs, water, feed and litter)were collected from six broiler farms located in different districts, SharkiaGovernorate (three farms used probiotic and other three farms not usedprobiotics).The collected samples were examined for determining theprevalence of Salmonella serotypes. Experimental study was done toevaluate the effect of probiotics (Lypholac & Sambiogen) on occuranceand mean count of S.typhimurium in caecum of healthy and experimentallyinfected broilers with S.typhimurium strains. Also, the effect of previousprobiotics on broiler performance with and without S.typhumuriuminfection was conducted.The obtained results were summarized as follows:1- Examination of 260 cloacal swabs, water, feed and litter samplescollected from three broiler farms without using probiotic at Sharkiagovernorate, Salmonella was recovered from 7 samples with overallprevalence 2.69%. Moreover, the overall percentages of Salmonella in thefarm No. 1, 2 and 3 were 3%, 2.5% and 2.5% respectively. The serotypingof respective isolated Salmonella strains was identified as five strainsS.entritidis and two strains S.agama.Generally, Salmonella was isolated from cloacal swabs, feed andlitter in a percentage of 42.86% (3 out of 7), 14.29% Cl out of 7) and42.85% (3 out of 7) respectively, but no Salmonella was detected inexamined water samples. Three isolate recovered from cloacal swab wasrepresented as one isolate S.Entritidis and other two was S.Agama, but .