Genomic DNA obtained from nine strains categorized of seven species ofmarine pathogenic Vibrio species were examined to determine whether themethylation of adenine residue occurred at GATC sequence.Several restrictionendonucleases,such as Sau3AⅠ,MboⅠ,DpnⅠ and BclⅠ,were used.In thepresent communication,we demonstrated that all pathogenic vibrios testedwere Dam phenotype,which presented 6-methyladenine at GATC sequence.The mechanism and the biological significance of adenine methylation occurredin marine pathogenic vibrios remain to be studied.