Vibrio vulnificus, a halophilic vibrio is an estuarine gram-negative bacteria that is associated with severe and frequently fatal wound infections and life-threatening septicemia. Bacteriocins are defined as antibacterial substance produced by various species of bacteria which are usually active against closely related organisms. Bacteriocins have found widespread application in epidemiological studies as specific markers of bacteria. It was proposed by Ha et al. (1990. J. Korean. Soc. Microbiol. 25: 586.) to give the bacteriocins produced by V. vulnificus the name "vulnificins". In the present study, a total of 72 strains of V. vulnificus isolated from patients and oysters were subjected to screen potential producers and indicators of vulnificin, applying ultraviolet induction method. Sensitivity of several strains of Serratia marcesans, Pseudomonas aeruginosa, Shigella flexneri, Salmonella typhi and Yersinia enterocolitica to vulnificins were also examined out. All the tested strains of V. vulnificus produced vulnificins active against indicator strains with various different inhibitory patterns. The spectrum of vulnificin activity and sensitive spectrum of indicator strains were considerably broad. Interestingly, almost all strains of S. marcescens, P. aeruginosa, Salmonella sp., Shigella sp. and Y. enterocolitica tested were sensitive to 1-7 vulnificin(s). Taken together, the present study demonstrated that all of the isolates of V. vulnificus produced vulnificins and that 8 good vulnificin producers and 10 good indicators were detected. These strains can be employed efficiently for establishing vulnificin typing scheme of V. vulnificus and for the detection of bacteriocinogeny and sensitivity in V. vulnificus. Biological role of vulnificin remains to be further elucidated.