Vibrio parahaemolyticus in retail shell oysters were investigated in the warmer months. From April to August 2003,113 oysters in shell were sampled monthly in Fuzhou and Xiamen of Fujian province,China (36% from restaurants;46% from retail markets and 18% from wholesale seafood markets). The V. parahaemolyticus in oyster samples was determined qualitatively and quantitatively by the Vitek identification system and the most probable number technique. The geometric mean V. parahaemolyticus density in retail shell oysters was 60 MPN/100 g,with 41.6% had V. parahaemolyticus densities below the detectable level of 30 MPN/100 g;only two samples from Xiamen were found to harbor V. parahaemolyticus densities exceeding \{24 000 MPN/100 g.\} There were significant differences in the V. parahaemolyticus densities among different regions,sampling sites and months ( P <0.01). Oysters from Xiamen had higher densities of V. parahaemolyticus than did oysters collected from Fuzhou. The highest mean V. parahaemolyticus density was observed in samples from wholesale seafood market. The highest mean V. parahaemolyticus density was observed in samples collected in May (149 MPN/100 g) while approximately 40 MPN/100 g was observed in samples collected in June and August. High frequency of V. parahaemolyticus was detected in retail shell oysters. It is concluded that this organism needs to be intensively monitored and controlled in raw seafoods.