Abstract： A solution culture experiment was carried out in greenhouse to study the dynamic changes in antioxidative systems inroots of tomato seedlings ( Lycopersicom esculentum Mill. ) under zinc stress and recovery. The results showed that under stressmalonaldehyde (MDA) and protein contents increased, and the activities of superoxide dismutase (SOD, EC 1.15.1.1 ) , cat-lase (CAT, EC 1.11.1.6) and glutathione peroxidase ( GPX, EC 1.11.1.9) increased, while guaiacol peroxidase ( POD,EC 1.11.1.7 ) activity declined. AsA - GSH cycle was affected. Ascorbate peroxidase ( APX, EC 1.11.1.11 ) activity rose inthe first three days and decreased then, and glutathione reductase ( GR, EC 1.6.4.2) activity decreased in the first five daysand increased then, the contents of ascrobate (AsA) and glutathione (GSH) increased as well. After recovery, MDA and pro-tein contents declined to control level. The activities of POD and APX increased, while the activities of SOD, CAT and GR andGSH content increased in the beginning of recovery, and then decreased. GPX activity and AsA content in roots duratively de-clined. After recovery the activities and contents remained higher than those of controls. According to the results of the experi-ment, the role of AsA - GSH cycle during the stressed and recovering period was discussed in this paper. Fig 3, Ref 16