History and Objectives: Salmonellosis is the most prevalent food born disease in the world and poultry meat is one of the sources of infection. Suspicion of food born Salmonellosis is always present. In order to determine the prevalence of Salmonellosis in poultry carcass and the effect cool-suspension was studied in a industrial slaughter house in Tehran in 1994.

Materials and Methods: A descriptive study in the first phase and an experimental study in the second phase was carried out. Isolation of Salmonella: Carcass samples were randomly selected for microbiological examination on selective enriched culture media, selective solid media and differential nonselective media. Isolation of the suspected cultured cells, biochemical and serologic tests were done for final confirmation of isolated Salmonella. The prevalence of the contamination of samples were determined and confidence interval were estimated for the population. Mc Nemar test was performed to test the efficacy of the cooling effect.

Results: Salmonella contamination was 57.7% for poultry carcass before cooling and the cooling effect raised the rate of contamination by 12.5% (P<0.07). Forty percent increase in the rate of infection was observed in the water tank.

Conclusion: The most prevalent serotypes were S.typhimurium and S.enteritidis. In order to reduce the rate of contamination, it is suggested the bacterial examination of chicken breeding, poultry house, feed producing factories, slaughterhouses and personal and staff working in these industries ought to carried out.