Abstract: Objective This study was conducted to investigate the pathogenic characteristics of sporadic cholera cases in Dandong City from 2004 to 2005 and the relationship with Vibrio cholerae detected from seawater and seafood. Methods The combination of serological and biochemical tests were applied to work over the biochemical characteristics,molecular typing,cluster analysis and cholera toxin (CTX) gene carrying status of Vibrio cholerae of different serotypes and phage-biotypes. Results All the Vibrio cholerae with the phage-biotype of prevalent strain (1b,1d) were toxin-producing strains with a CTX gene carrying rate of 100 % and none of the non-prevalent strain was found to carry CTX gene. PFGE molecular typing and cluster analysis showed a high genetic association between the strains isolated from the patients and those from the seawater and seafood. Conclusion The vibrio cholerae found in Dandong has high pathogenicity. The V. cholerae pollution of water and seafood is the key to the occurrence of cholera cases,and a vicious circle of pollution-infection has come into being. People's unhygienic habits and hesitation in seeking medical care exacerbate this cycle and to a large extent makes it difficult to control and treat cholera.