Surviving Salmonella Typhimurium (S. Typhimurium) cells in mayonnaise were monitored during storage at 10 to 40oC at pH of 3.7 and 4.0. The survival of S. Typhimurium in mayonnaise was influenced by pH and storage temperature. The fastest decline in the viability of S. Typhimurium was observed at 40oC and the slowest decline was observed at 10oC. Death rates were faster at pH 3.7 than at pH 4.0 at the same temperature, except for 30 and 40oC. With all experimental variables, linear regression analysis showed a good fit (r2=0.8564 to 0.9904). This model is appropriate for predicting death rates on the basis of a coefficient of determination of r2=0.87, a mean square error of 0.00055, a bias factor of 1.0112, and an accuracy factor of 1.30958. Our model provides a reliable prediction of the death rate of S. Typhimurium in mayonnaise based upon the combined effects of temperature and pH.