We developed a fluorescent real-time quantitative RT-PCR method to evaluate the pattern ofmRNA expression in response to the bacterial infection in the oyster (Vibrio alginolyticus, and measured gene expression in six tissues (mantle, gills, digestive gland, muscle, heart and ). We measured the accumulation and distribution of mRNA expression was gene expression increased significantly at in the gill. Similarly, levels peaked at 6 h in the digestive gland then remained high until 24 h, after which they decreased rapidly to control levels. mRNA expression was ~10 fold higher in the haemocytes than the control after 3 h, and the expression evels (~15 fold higher than the control). The was ~2.5 fold higher in the remaining tissues than in the control. though levels had declined by 6 h. The accumulation of bacteria in the muscle increased at 12 h and remained high up to 72 h. concentration was time-dependent in the digestive gland whereas the bacteria correlation between mRNA expression and the concentration of bacteria, most obvious in the digestive gland.Our results suggest that bacterial challenge induces the up-regulation of mRNA expression and suggests that HSC70 plays an important role in protecting the oyster against the bacterial pathogen.