Home-made type mayonnaise and commercial type mayonnaise were inoculated with 10⁵/g of 4 phage types of Salmonella Enteritidis (SE), isolated from unpasteurized whole eggs, and the behavior of SE was examined. At 30°C the number of SE in home-made mayonnaise decreased to less than 10/g after 5-6 days, and decreased to the same level after 1 day in commercial type mayonnaise. At 10°C the number of SE inoculated into home-made type mayonnaise hardly decreased after 9 days, and decreased to less than 10/g after 3-6 days in commercial type mayonnaise. The difference between the phage types was not so large. SE inoculated into a delicatessen plant type mayonnaise showed the same behavior as that inoculated into commercial type mayonnaise. In potato, egg, and crab salads containing 15% home-made type mayonnaise, in which SE was still surviving, SE grew rapidly at 25°C, but hardly grew at 10°C. The importance of using pasteurized yolk in commercial mayonnaise, and a low storage temperature for salads was recognized.