The ubiquity of Vibrio spp. throughout the coastal marine waters of the Pacific Northwest of North America raises questions about the susceptibility of native marine fishes, including Pacific herring (Clupea pallasii). Early reports of Vibriolike disease (Rucker et al., 1954; Walford, 1958) and Vibrio sp. isolations (Pacha & Kiehn, 1969) in Pacific herring remain questionable because both occurred while the classification of vibrios was still developing and prior to the availability of techniques capable of discerning viral aetiologies. This study was performed to address these uncertainties by determining the susceptibility of Pacific herring to vibriosis caused by strains of V. anguillarum and V. ordalii.