Vibrio parahaemolytieus, a Gramnegative facultative anaerobe, possesses a phosphoenolpyruvate:glucose phosphotransferase system (glucose-PTS) consisting of at least 4 protein components tentatively designated I, H, III and II [1]. Although exact characterization of these components has not been accomplished, several lines of evidence thus far obtained [1] all point out that they probably correspond to, respectively, enzyme I, HPr, factor III Glc and enzyme II (or II-B) Glc described for other bacteria such as Escherichia coli, Salmonella typhimurium, and Staphylococcus aureus [21. The soluble specific component III (or factor III Gjc) of the organism, however, seemed to be shared by both glucoseand trehalose-PTSs; mutants devoid of this component were defective in both glucose.and trehalose-PTS activities, while mutants lacking the membrane-bound component II (or enzyme II ':;l~) were defective only in glucosePTS activity [1]. It was expected, therefore, that the organism might possess a trehalose-specific membrane-bound component (enzyme II Tre), being distinct from enzyme II Glc and specifically involved in trehalose phosphorylation. In this report, mutational evidence for the existence of enzyme II Tr~ in V. parahaemolyticus is presented. The data also suggest that the presumed enzymes II Gle and II Tre of the organism show some cross specificity for the substrate of each other.