Technical Abstract: Commercial scale field trials utilizing an undefined mucosal competitive exclusion (MCE) flora to diminish salmonellae associated with poultry have been conducted in Puerto Rico and in Georgia. In these field trials, a two-step treatment of broiler chicks with MCE, first sprayed on the chicks in the matching cabinet, followed by administration in the first drinking water, was evaluated. In Puerto Rico, three commercial flocks were treated and compared with parallel, untreated control flocks. Following a 7 week growing period, birds in both control and treated groups were analyzed for salmonellae prevalence before and after processing. Salmonella prevalence in processed carcass rinses were significantly (p <0.05) reduced from 41% in control flocks to 10% in treated flocks. In Georgia, 11% of untreated processed chickens were Salmonella positive compared to 5% of MCE treated chicks. To assure reduction of salmonellosis associated with consumption of undercooked or mishandled chicken, salmonellae-free chickens should be grown and delivered to the processing plant and competitive exclusion provides a realistic opportunity to achieve this.