Abstract: Dong(D) lake,Han(H) river and Yangtze(Y) river are main water supplies of the city of Wuhan. In the present study the effect of organicextracts of chlorinated drinking water(CDW) processed from rawwater of D lake,H river and Y river on lipid peroxidation(LPO) was evaluated in human HepG2 cells to explore the possible mechanism of cell damage caused by CDW extracts. HepG2 cells were exposed in vitro to CDW extracts of concentrations corresponding to 0. 167, 1. 67, 16. 7 and 167ml CDW/ml culture medium. As a product of LPOand an intracellular antioxidant,malondialdehyde(MDA) and glutathione(GSH)were determined in HepG2 cells after CDW extracts treatment. DMSO(7μ l/ml culture) and H2O2(100μ mol/L) were used as solvent control and positive control respectively. HepG2 cells exhibited significant increase of MDA levels(0. 062 ±0. 015,0. 065 ±0. 012 and 0. 070 ±0. 014μ g/mg protein) after treatment of CDW extracts from D lake for 16. 7 and 167ml CDW/ml culture and H riverfor 167ml CDW/ml culture in comparison with DMSO solvent control(0. 029 ±0. 003μ g/mg protein). No significantly enhanced levels of MDA were observed in HepG2 cells exposed to CDW extracts from Y river. Additionally,all the concentrations of CDW extracts fromD lake for0. 167,1. 67,16. 7 and 167ml CDW/ml culture lead to significant decreased GSH(0. 048 ±0. 006,0. 043±0. 003,0. 042 ±0. 001 and 0. 042 ± 0. 006μ g/mg protein) compared to the DMSO solvent control(0. 062 ±0. 001μ g/mgprotein). GSH decrease was also found at the higher concentrations of CDW extracts fromH river and Y river for16. 7 and 167mlCDW/ml culture. Statistical analysis showed a inverse correlation between the levels ofMDA and GSH in HepG2 cells aftertreatment of CDW extracts fromD lake,Y river and H river. The results indicated that CDW extracts could have obvious LPO effect on HepG2 cells in vitro. CDW extracts from D lake showed stronger LPO effect than those from H river and Y river.