The behavior of 15 strains of Vibrio eltor, halophilic Vibrios and NAG vibrios with respect to 14 antibiotics was studied by means of the single disc method in Mueller-Hinton agar. In the case of fosfomycin, the MIC for all of them was determined as well by the technique of progressive dilutions in solid medium. No conclusions were made because of the small number of strains studied. Nevertheless, it can be asserted that there is a marked difference in the activity of fosfomycin, since it was minimal against V. eltor, moderate against the NAGs and maximal against the halophilic Vibrio.