The major purpose of the present study is to survey vegetables, meats, seafoods, processed foods and imported foods for the presence. of Listeria spp. and to prevent listeriosis caused by the contamination of Listeria monocytogenes. Listeria spp. was isolated from 6.0% of meats, 3.4% of seafoods, and 11.4% of imported foods but was not found in vegetables and processed foods. The optimum growth condition of isolates indentified as Listeria monocytogenes was pH 7.0 and 37℃. The antimicrobial effect of grapefruit seed e×tract (GFSE) was observed in the level of more than 100ppm by disk method. When lml(2.5× 10^6 CFU/ml) of Listeria monocytogenes was inoculated and incubated for 3 days at 30, the total cell number of the organism was 4.5 × 10^9 in the control, 7.2 × 10³ in 100 μg/ml of GFSE medium, and 3.5 μg/ml of GFSE medium. Direct visualization of microbial cells by using both transmission electron microscope and scanning electron microscope showed microbial cell membrane the function of which was destroyed by treating with the dilute solutions of GFSE. It could be confirmed that GFSE completely inhibited the growth of the test strain of Listeria monocytogenes.