An oligonucleotide DNA probe based on 5S rRNA sequence data was constructed for the identification of the fish pathogens, Vibrio anguillarum and Vibrio ordalii. Specificity of the probe was tested in a colony blot hybridization assay. The respective probe was found to be specific for both V. anguillarum and V. ordalii. No cross hybridization was observed against other fish pathogens and the closely related Vibrionaceae genera. This specific probe may be useful for rapid identification of V. anguillarum and V. ordalii.