Vibrio vulnificus is a pathogenic, estuarine bacterium associated with primary septicemia and severe wound infections. Previous studies have reported limited success in the introduction of plasmids into V vulnificus by conjugation, and there have been no reports of successful electroporation procedures. We report here on the introduction of recombinant plasmids into four strains of V. vulnificus by electroporation. In contrast to the complex medium that others have used for the electroporation of Vibrio cholerae, the efficiency of transformation of V. vulnificus was greatly improved by the use of a defined growth medium containing glucose. The addition of glycine betaine further enhanced transformant yield.