To understand the serotype and the virulent genotype of the Vibrio parahaemolyticus isolated from different sources in Zhejiang Province, the serotype was tested by serum agglutination; PCR technology was applied to measure the TDH (thermostable directs hemolysin) virulence gene. It was found that the serotypes of Vibrio parahaemolyticus isolated from clinical patients were distributed in 7 O-antigen groups. Among them, O3 was the dominating type with 71.81% prevalence in the isolations from clinical patients, and the proportion of O4 type rose to some extent accounting for 16.60% compared with last year. The serotype in strains isolated from seafoods distributed in 8 O-antigen groups, in which the O5 type prevailed (47.30%). It was demonstrated that the virulence gene TDH could be detected to be 95.65% in clinical isolations employing the PCR technology. In contrast, there was only 6.06% TDH positive rate in strains isolated from seafoods. Moreover, the TDH positive rate varied with the source of the bacteria despite of sharing the same serotype. There was difference in serotype and genotype of TDH between Vibrio parahaemolyticus strains isolated from seafoods and from patients suffering from foodborn disease.