Fishery products were collected in seafood markets located on the southwestern coast of Korea between 2000 and 2004 and examined for the presence of Vibrio parahaemolyticus. This strain was detected in 138 of 843 samples (16.4%) that included dams, eels, crabs, octopuses, and cockles. The number of positive findings for V. parahaemolyticus among fishery products was the highest in dams at 23.6% followed by eels at 22.1%, crabs at 21.1%, octopuses at 18.0%, and cockles at 14.3%. V. parahaemolyticus was detected with overall frequencies of 15.3, 14.8, 13.8, 21.6, and 18.6% from 2000 to 2004, respectively. The monthly occurrence of the organism rapidly increased to over 20% between June and October. The monthly cases of food borne disease caused by V. parahaemolyticus in Korea over the last five years began to increase in August and reached its peak in September. However, the potential for outbreaks of food borne disease caused by V. parahaemolyticus was relatively minor between November and April. Consequently, this study shows that fishery products harvested from June to October must be handled sanitarily in Korea.