Vibrio parahaemolyticus is a halophilic gram-negative bacterium that causes food borne acute gastroenteritis in human being or certain diseases in aquatic species. In addition to thermostable direct hemolysin (tdh) and tdh-related hemolysin (trh), two sets of type III secretion systems (T3SS) were recently found to be associated closely with virulence. T3SS1 located on chromosome 1 is involved in cytotoxicity to host cells and orchestrates a multifaceted host cell infection by induction of autophagy, cell rounding, and eventual cell lysis. T3SS2 in chromosome 2 is enterotoxic. In this we address the composition of the two T3SS, their functions and regulation in Vibrio parahaemolyticus.