Vibrio parahaemolyticus is a ubiquitous marine bacterium and also a human pathogen. This organism is frequently isolated from a variety of raw seafoods. Consumption of raw or undercooked seafood contaminated with V. parahaemolyticus is responsible for the development of acute gastroenteritis. Several virulence factors have been identified in this pathogen, of which the thermostable direct hemolysin (TDH), TDH-related hemolysin, and type III secretion system are considered very important. Emergence and spread of O3:K6 serovar in 1996 was designated as a pandemic strain of V. parahaemolyticus. Other serovars such as O4:K68, O1:K25, and O1:KUT were found genetically similar and thought to have evolved from the pandemic strain of O3:K6. These pandemic serovars have spread in many Asian, European, and American countries.