Enterohemorrhagic Escherichia coliO157 : H7 (Ex-1064) were inoculated into various foods such as minced meat, milk, fruit juice, and other commercial foods. During the storage at-20°C for 15 days, the survival number of inoculum was periodically assessed. Furthermore, the influence of foods thawing process on the residual number of inoculated E. coli O157 : H7 was tested. (1) The foods tested were roughly classified into three groups as follows by the behaviors of residues. (1) Group A-1 foods : The survival number remained constant during 15 days : minced meats (beef, pork, chicken, hamburger meat and fish). (2) Group A-2 foods : The survival number gradually decreased in 15 days : milk, bouillon, corn potage, white sauce, mashed potato, boiled fish paste (kamaboko), bean curd, fried bean curd (atuage), omelet and boiled rice. (3) Group B foods : The number of inoculum decreased rapidly and disappeared within one day : fruit juice and acidic sauce (apple juice, orange juice, soy sauce, Worcestershire sauce, demiglace sauce, French dressing, Italian dressing, and Thousand Island dressing). (2) For the studies of the influence of food thawing process on the residual number of E. coli O157 : H7, inoculations were carried out into both Group A-1 foods, minced beef, and also Group A-2 foods such as milk and bouillon. However, there was no difference in the number of residues among the thawing process in the tap water, in the refrigerator, and at room temperature.