Effects of BDE-47 on gene expression levels of AhR, CYP4, GST-pi and Pgp of the gills and digestive glands of clam were studied in a 21-day exposure test. The results showed that the no significant change in the control clams during the exposure. AhR mRNA expression levels reached maximum and minimum at day 6 and day 1. mRNA gene expressionreached the peak value at . GST-pi mRNA expression levels in 0.25 µg/L BDE-47 group are significantly higher than control levels, while in 6.25µg/L BDE-47 treatments are significantly lower than Pgp mRNA expression levels in all BDE-47 treatment groups are significantly higher than Significant dose and time-dependent relationship between the expression levels of GST-pi mRNA and BDE-47 exposure doses were found in the results, indicating that GST-pi mRNA expression in the gills and digestive glands of can be considered as a potential biomarker which can be used to evaluate BDE-47 pollution in seawater.