The ionizing radiation resistances of sixSalmonella species were examined. The experimental variables were the suspending medium, the presence or absence of air, and the temperature during the irradiation process.S. typhimurium ATCC 14028,S. enteritidis ATCC 9186,S. newport ATCC 6962,S. dublin ATCC 15480,S. anatum ATCC 9270, andS. arizonae ATCC 29933 were suspended in phosphate buffer (0.1 M, pH 7.0), brain heart infusion broth (BHI) or mechanically deboned chicken and exposed to gamma radiation from cesium-137 at 0.12 kGy per min. The radiation resistance of theSalmonella increased approximately two-fold when assayed in sterile mechanically deboned chicken rather than in buffer or BHI. The average radiation (0.30 to 1.20 kGy) D-value for all sixSalmonella strains was 0.56 kGy in mechanically deboned chicken.S. enteritidis was significantly more resistant to ionizing radiation than the other five strains ofSalmonella tested on mechanically deboned chicken. The temperature of irradiation but not the presence or absence of air significantly influenced the survival ofS. typhimurium andS. enteritidis in mechanically deboned chicken. Treatment of chicken meat with ionizing radiation would be an effective means for control ofSalmonella contamination.