Recent outbreaks of Vibrio parahaemolyticus infections in North America were due to consumption of raw oysters. All clinical isolates possessed the tdh gene common to pathogenic strains. Although gene detection in pure cultures by PCR is very efficient, inhibitors present in oysters interfere with the PCR reaction and prevent detection of low numbers of pathogenic V. parahaemolyticus. In this study, the detection limits of different methods (boiling, boiling/Chelex, phenol:chloroform:isoamyl alcohol, CTAB/NaCl, GITC/chloroform, GuSCN/diatomaceous earth, and PERFECTg DNA filters) for extraction of DNA from enrichments of oyster homogenates were compared using PCR. Freshly harvested and retail market oysters (Crassostrea virginica) were homogenized (1:10 oyster:APW), inoculated with 0 to 103 CFU/g of tdh+ V. parahaemolyticus, and enriched overnight at 35° C. The CTAB/NaCl method was the most efficient for extraction of DNA from fresh oyster enrichments. Detection limits for pathogenic V. parahaemolyticus were 100 to 101 CFU/g in initial inocula (104 to 108 CFU/g after enrichment). The same numbers of cells (100to 101 CFU/g) were detectable in only 20% of inoculated market oysters, perhaps due to overgrowth of the pathogenic strain by inherent microflora or the presence of other PCR inhibitors.