Vibrio parahaemolyticus was isolated from 47 of 2,699 stools examined primarily for the exclusion of cholera. All strains grew well in alkaline peptone water containing 0.5% NaCl and in Monsur's medium. Serotyping showed them to be of various types. Adults were mainly affected. The importance of looking for V. parahaemolyticus in clinical specimens from cases of diarrhea is emphasized.