A hydroponic culture experiment was done to investigate the effect of Cd stress on glutathione content (GSH) and glutathione S-transferase (GST, EC 2.5.1.18) activity in rice seedlings. The rice growth was severely inhibited when Cd level in the solution was higher than 10mg/L. In rice shoots, GSH content and GST activity increased with the increasing Cd level, while in roots, GST was obviously inhibited by Cd treatments. Compared with shoots, the rice roots had higher GSH content and GST activity, indicating the ability of Cd detoxification was much higher in roots than in shoots. There was a significant correlation between Cd level and GSH content or GST activity, suggesting that both parameters may be used as biomarkers of Cd stress in rice.