This study was conducted to decent-line the prevalence of Listen monocytogenes in retailed meats, comprising beef. chicken, and pork. in the Tokyo metropolitan area. A total of 379 samples of retailed meat were collected from 1998 to 2003, most of which were obtained by simultaneously purchasing the three classes of meat from a shop and then making another simultaneous purchase of meat from the same shop a few weeks later The prevalence of L monocytogenes was 28.0%, and the serotypes isolated were mainly 1/2a, 1/2b, 1/2c. and 4b Comparison of the prevalence of each scrotype among the classes of meat showed a predominant distribution of serotypes 1/2a. 1/2b, and 4b in chicken, while serotype 1/2c was dominant in pork. A total of nine cases considered to be due to persistence and/or cross-contamination were found Most of the strains involved in persistence and/or cioss-contamination were of serotypes 1/2c or 4b These results suggest that contamination in retailed meat in Japan is at almost the same level as in other countries and that chicken has the highest potential as a source of contamination and infection In addition, we suggest that the ecological niche of serotype 1/2c is distinct from those of 1/2a. 1/2b. and 4b. which may explain why human hosts have less opportunity to be exposed to serotype 1/2c and why there is a lower rate of isolation of this serotype from cases of human listeriosis.