Aims: The aim of this research was to identify and partially purify new bacteriocin-like substances from strains of halophilic 'non-cholera' vibrios isolated from food sources. Methods and Results: Forty-five halophilic Vibrio spp. strains were screened for antimicrobial production. Vibrio mediterranei 1, a nonpathogenic strain, showed antimicrobial activity towards Vibrio parahaemolyticus spp. and related species. The bacteriocin-like inhibitory substance (BLIS), released by the bacteria into growth media, was concentrated by ultrafiltration and characterized. BLIS was sensitive to proteinase K, was stable in the pH range 5-9, was resistant to organic solvents and was heat stable up to 75 degrees C. Initial purification of BLIS by size exclusion chromatography showed an apparent molecular mass of 63-65 kDa. Conclusions: This study reports the ability of V. mediterranei 1 to produce a bacteriocin-like substance inhibiting growth of V. parahaemolyticus spp. and other closely related bacteria. Significance and Impact of the Study: The strong activity of BLIS towards the human and fish pathogen V. parahaemolyticus and the persistence of antimicrobial properties under a variety of different conditions suggest its potential application in food microbiology.