Abstract: Low density lipoprotein(LDL)was oxidized with Cu²⁺ in vitro.A lag phase was followed by oxidave modification after addition of CuCl₂, and about 15 h,the reaction reach a peak.LDL oxidation was continuously monitored spectrophotometrically at 234 nm to follow the formation of conjugated dienes.Three phases were found in oxidation curve:Lag phase, propagation phase and decomposition phase.By determinating thiobarbituric acid reaction substances(TBARS),we found the lipid peroxidation increased as much as 15 times in LDL.

Key words: low density lipoprotein, oxidative modification, conjugated dienes, thiobarbituric acid reaction substances(TBARS)