Abstract: We studied the bioaccumulation characteristics and antioxidant enzymes activity changes of Manila clam, Ruditapes philippinarum under the exposure to cadmium (Cd) and copper (Cu). The bioconcentrations of Cd and Cu in gill and hepatopancreas of R. philippinarum showed obvious time and dose dependent responses. The clam showed higher bioaccumulation ability on Cd than that of Cu, and the heavy metal concentrations in hepatopancreas were greater than those in gill. Additionally, the activities of superoxide dismutase (SOD), glutathione peroxidases (GPx) and glutathione stransferases (GST) were significantly promoted in hepatopancreas and gill of R. philippinarum at different concentrations and time intervals (P < 0.05), while the activities of SOD and GST were significantly inhibited at high concentrations of Cd and Cu (P < 0.05). The activities of GPx recovered to the original level with the time progressed. Taken together, the changes of SOD and GST activities in hepatopancreas and gills of R. philippinarum could be considered as potential biomarkers for copper and cadmium contamination in the marine environment.