The Special Bacteriology Section of the Center for Disease Control has received 38 cultures of a halophilic bacterium which apparently unnamed. On the basis of the minimal characteristics of Vibrio species proposed by Hugh and Sakazaki, this bacterium belongs to the genus Vibrio. The unnamed species can be differentiated from Vibro parahaemolyticus by a lower tolerance for sodium chloride (NaC1) and the fermentation of lactose. The failure to ferment sucrose is an additional characteristic which differentiates these organisms from V. alginolyticus. Of 33 unnamed species strains tested, all were sensitive to penicillin, ampicillin, carbenicillin, cephalothin, chlorapmphenicol, gentamicin, tetracycline, rifampin, nitrofurantoin, and sulfisoxazole by agar diffusion and agar dilution tests. The sources of isolation of the cultures of the unnamed species suggest that it is a clinically important organism. Twenty strains were isolated remaining cultures were isolated from localized infections of the extremities. In contrast, only 2 of 60 cultures of V. parahaemolyticus and V. alginolyticus received in our laboratory as human isolates from extra-intestinal sources were isolated from blood.